## SYNOPSIS

           blt::vector create vecName ?vecName...? ?switches?

           blt::vector destroy vecName ?vecName...?

           blt::vector expr expression

           blt::vector names ?pattern...?

## DESCRIPTION

           The vector command creates an array of floating point values.  The vec-
           tor's components can be manipulated in three ways: through a Tcl  array
           variable, a Tcl command, or the C API.

## INTRODUCTION

           A vector is an ordered set of real numbers.  The components of a vector
           are indexed by integers.

           Vectors are common data structures for many applications.  For example,
           a  graph  may  use  two vectors to represent the X-Y coordinates of the
           data plotted.  The graph will automatically be redrawn when the vectors
           are  updated or changed. By using vectors, you can separate data analy-
           sis from the graph widget.  This makes it easier, for example,  to  add
           data  transformations, such as splines.  It's possible to plot the same
           data to in multiple graphs, where each graph presents a different  view
           or scale of the data.

           You  could  try to use Tcl's associative arrays as vectors.  Tcl arrays
           are easy to use.  You can access individual elements randomly by speci-
           fying  the  index,  or  the set the entire array by providing a list of
           index and value pairs for each element.  The disadvantages of  associa-
           tive  arrays  as  vectors  lie in the fact they are implemented as hash
           tables.

           o There's no implied ordering to the associative arrays.  If  you  used
             vectors  for  plotting, you would want to insure the second component
             comes after the first, an so on.  This isn't  possible  since  arrays
             are actually hash tables.  For example, you can't get a range of val-
             ues between two indices.  Nor can you sort an array.

           o Arrays consume lots of memory when the  number  of  elements  becomes
             large  (tens of thousands).  This is because each element's index and
             value are stored as strings in the hash table.

           o The C programming interface is unwieldy.  Normally with vectors,  you
             would  like to view the Tcl array as you do a C array, as an array of
             floats or doubles.  But with hash tables, you must convert  both  the
             index  and  value to and from decimal strings, just to access an ele-
             ment in the array.  This makes it cumbersome to perform operations on
             the array as a whole.

           The  vector  command  tries to overcome these disadvantages while still
           0.0.  In addition, both a Tcl command and array variable, both named y,
           are created.  You can use either the command or variable  to  query  or
           modify components of the vector.  # Set the first value.  set y(0) 9.25
           puts "y has [y length] components" The array y can be used to  read  or
           set individual components of the vector.  Vector components are indexed
           from zero.  The array index must be a number less than  the  number  of
           components.  For example, it's an error if you try to set the 51st ele-
           ment of y.  # This is an error. The vector only has 50 components.  set
           y(50) 0.02 You can also specify a range of indices using a colon (:) to
           separate the first and last indices of the range.  # Set the first  six
           components  of y set y(0:5) 25.2 If you don't include an index, then it
           will default to the first and/or last component of the vector.  # Print
           out  all  the  components  of y puts "y = $y(:)" There are special non-
           numeric indices.  The index end, specifies the last  component  of  the
           vector.  It's an error to use this index if the vector is empty (length
           is zero).  The index ++end can be used to extend the vector by one com-
           ponent  and initialize it to a specific value.  You can't read from the
           array using this index, though.  # Extend the vector by one  component.
           set  y(++end)  0.02  The  other  special indices are min and max.  They
           return the current smallest and largest components of  the  vector.   #
           Print the bounds of the vector puts "min=$y(min) max=$y(max)" To delete
           components from a vector, simply unset the corresponding array element.
           In the following example, the first component of y is deleted.  All the
           remaining components of y will be moved down by one index as the length
           of  the  vector  is reduced by one.  # Delete the first component unset
           y(0) puts "new first element is $y(0)" The  vector's  Tcl  command  can
           also  be  used to query or set the vector.  # Create and set the compo-
           nents of a new vector blt::vector create x x set { 0.02 0.04 0.06  0.08
           0.10 0.12 0.14 0.16 0.18 0.20 } Here we've created a vector x without a
           initial length specification.  In this case, the length is  zero.   The
           set  operation  resets  the vector, extending it and setting values for
           each new component.

           There are several operations for vectors.  The  range  operation  lists
           the  components of a vector between two indices.  # List the components
           puts "x = [x range 0 end]" You can search for a particular value  using
           the  search  operation.  It returns a list of indices of the components
           with the same value.  If no component has the same  value,  it  returns
           "".   #  Find  the index of the biggest component set indices [x search
           $x(max)] Other operations copy,  append,  or  sort  vectors.   You  can
           append  vectors  or  new values onto an existing vector with the append
           operation.  # Append assorted vectors and values to x x append x2 x3  {
           2.3  4.5  }  x4 The sort operation sorts the vector.  If any additional
           vectors are specified, they are rearranged in the  same  order  as  the
           vector.   For example, you could use it to sort data points represented
           by x and y vectors.  # Sort the data points x sort y The  vector  x  is
           sorted  while  the  components of y are rearranged so that the original
           x,y coordinate pairs are retained.

           The expr operation lets you perform arithmetic on vectors.  The  result
           is stored in the vector.  # Add the two vectors and a scalar x expr { x
           + y } x expr { x * 2 } When a vector is modified, resized, or  deleted,
           Vectors are created using the vector create operation.  Th create oper-
           ation can be invoked in one of three forms:

           blt::vector create vecName
                  This  creates a new vector vecName which initially has no compo-
                  nents.

           blt::vector create vecName(size)
                  This second form creates a new vector which  will  contain  size
                  number  of  components.  The components will be indexed starting
                  from zero (0). The default value for the components is 0.0.

           blt::vector create vecName(first:last)
                  The last form creates a new  vector  of  indexed  first  through
                  last.   First and last can be any integer value so long as first
                  is less than last.

           Vector names must start with a letter and consist of  letters,  digits,
           or  underscores.   #  Error:  must start with letter blt::vector create
           1abc You can automatically generate vector names using the "#auto" vec-
           tor  name.   The  create  operation will generate a unique vector name.
           set vec [blt::vector create #auto] puts "$vec has [$vec length]  compo-
           nents"

       VECTOR INDICES
           Vectors  are indexed by integers.  You can access the individual vector
           components via its array variable or Tcl command.   The  string  repre-
           senting  the index can be an integer, a numeric expression, a range, or
           a special keyword.

           The index must lie within the current range of the vector, otherwise an
           an  error  message  is  returned.  Normally the indices of a vector are
           start from 0.  But you can use the offset operation to  change  a  vec-
           tor's  indices  on-the-fly.   puts  $vecName(0)  vecName offset -5 puts
           $vecName(-5) You can also use  numeric  expressions  as  indices.   The
           result  of  the expression must be an integer value.  set n 21 set vec-
           Name($n+3) 50.2 The following special non-numeric  indices  are  avail-
           able:  min,  max, end, and ++end.  puts "min = $vecName($min)" set vec-
           Name(end) -1.2 The indices min and max will return the minimum and max-
           imum values of the vector.  The index end returns the value of the last
           component in the vector.  The index ++end is used to append  new  value
           onto  the vector.  It automatically extends the vector by one component
           and sets its value.  # Append an new component  to  the  end  set  vec-
           Name(++end)  3.2 A range of indices can be indicated by a colon (:).  #
           Set the first six components to 1.0 set vecName(0:5) 1.0 If no index is
           supplied the first or last component is assumed.  # Print the values of
           all the components puts $vecName(:)

## VECTOR OPERATIONS

           blt::vector create vecName?(size)?... ?switches?
                  The create operation creates a new vector vecName.  Both  a  Tcl
                  command  and  array variable vecName are also created.  The name
                         then  no  variable  will be mapped.  You can always map a
                         variable back to the vector using the  vector's  variable
                         operation.

                  -command cmdName
                         Maps  a  Tcl  command  to  the  vector. The vector can be
                         accessed using cmdName and one  of  the  vector  instance
                         operations.   A  Tcl  command by that name cannot already
                         exist.  If cmdName is the empty string, no  command  map-
                         ping will be made.

                  -watchunset boolean
                         Indicates  that  the  vector  should automatically delete
                         itself if the variable  associated  with  the  vector  is
                         unset.  By default, the vector will not be deleted.  This
                         is different from  previous  releases.   Set  boolean  to
                         "true" to get the old behavior.

           blt::vector destroy vecName ?vecName...?
                  Deletes  one  or  more  vectors.  Both the Tcl command and array
                  variable are removed also.

           blt::vector expr expression
                  All binary operators take vectors  as  operands  (remember  that
                  numbers are treated as one-component vectors).  The exact action
                  of binary operators depends upon the length of the second  oper-
                  and.   If  the  second operand has only one component, then each
                  element of the first vector operand is computed by  that  value.
                  For  example,  the  expression "x * 2" multiples all elements of
                  the vector x by 2.  If the second operand has more than one com-
                  ponent,  both  operands  must  be the same length.  Each pair of
                  corresponding elements are computed.  So "x + y"  adds  the  the
                  first components of x and y together, the second, and so on.

                  The  valid  operators  are  listed  below, grouped in decreasing
                  order of precedence:

                  -  !                Unary minus  and  logical  NOT.   The  unary
                                      minus  flips  the  sign of each component in
                                      the  vector.   The  logical   not   operator
                                      returns  a vector of whose values are 0.0 or
                                      1.0.  For each  non-zero  component  1.0  is
                                      returned, 0.0 otherwise.

                  ^                   Exponentiation.

                  *  /  %             Multiply, divide, remainder.

                  +  -                Add and subtract.

                  <<  >>              Left and right shift.  Circularly shifts the
                                      values of the vector (not implemented  yet).

                  &&                  Logical AND.  Produces a 1  result  if  both
                                      operands are non-zero, 0 otherwise.

                  ||                  Logical OR.  Produces a 0 result if both op-
                                      erands are zero, 1 otherwise.

                  x?y:z               If-then-else, as  in  C.   (Not  implemented
                                      yet).

                  See  the  C  manual  for more details on the results produced by
                  each operator.  All of the binary operators group  left-to-right
                  within the same precedence level.

                  Several  mathematical functions are supported for vectors.  Each
                  of the following functions invokes the math library function  of
                  the  same name; see the manual entries for the library functions
                  for details on what they do.  The operation is  applied  to  all
                  elements     of    the    vector    returning    the    results.
                  acos    cos     hypot   sinh        asin    cosh    log     sqrt
                  atan    exp     log10   tan ceil    floor   sin     tanh

                  Additional functions are:

                  abs       Returns the absolute value of each component.

                  random    Returns a vector of non-negative values uniformly dis-
                            tributed between [0.0, 1.0) using drand48.   The  seed
                            comes from the internal clock of the machine or may be
                            set manual with the srandom function.

                  round     Rounds each component of the vector.

                  srandom   Initializes the random number generator using srand48.
                            The high order 32-bits are set using the integral por-
                            tion of the first vector component. All  other  compo-
                            nents  are  ignored.  The low order 16-bits are set to
                            an arbitrary value.

                  The following functions return a single value.

                  adev      Returns the average deviation (defined as the  sum  of
                            the  absolute values of the differences between compo-
                            nent and the mean, divided by the length of  the  vec-
                            tor).

                  kurtosis  Returns  the  degree  of peakedness (fourth moment) of
                            the vector.

                  length    Returns the number of components in the vector.

                  max       Returns the vector's maximum value.

                  skew      Returns  the skewness (or third moment) of the vector.
                            This characterizes the degree of asymmetry of the vec-
                            tor about the mean.

                  sum       Returns the sum of the components.

                  var       Returns  the  variance  of  the vector. The sum of the
                            squared differences between  each  component  and  the
                            mean  is computed.  The variance is the sum divided by
                            the length of the vector minus 1.

                  The last set returns a vector of the same length  as  the  argu-
                  ment.

                  norm      Scales  the  values  of the vector to lie in the range
                            [0.0..1.0].

                  sort      Returns the  vector  components  sorted  in  ascending
                            order.

           vector names ?pattern?

## INSTANCE OPERATIONS

           You  can  also use the vector's Tcl command to query or modify it.  The
           general form is vecName operation  ?arg?...   Both  operation  and  its
           arguments  determine the exact behavior of the command.  The operations
           available for vectors are listed below.

           vecName append item ?item?...
                  Appends the component values from item to vecName.  Item can  be
                  either the name of a vector or a list of numeric values.

           vecName binread channel ?length? ?switches?
                  Reads  binary  values  from  a  Tcl  channel.  Values are either
                  appended to the end of the vector or placed  at  a  given  index
                  (using  the  -at  option), overwriting existing values.  Data is
                  read until EOF is found on the channel or a specified number  of
                  values  length  are  read (note that this is not necessarily the
                  same as the number of bytes). The following  switches  are  sup-
                  ported:

                  -swap  Swap  bytes  and  words.   The default endian is the host
                         machine.

                  -at index
                         New values will start at vector index index.   This  will
                         overwrite any current values.

                  -format format
                         Specifies  the  format of the data.  Format can be one of
                         the following: "i1", "i2", "i4", "i8", "u1,  "u2",  "u4",

                  This is useful when the vector is large.

           vecName delete index ?index?...
                  Deletes the indexth component from the vector vecName.  Index is
                  the  index  of  the  element to be deleted.  This is the same as
                  unsetting the array variable element index.  The vector is  com-
                  pacted after all the indices have been deleted.

           vecName dup destName
                  Copies  vecName  to destName. DestName is the name of a destina-
                  tion vector.  If a vector destName already exists, it  is  over-
                  written  with the components of vecName.  Otherwise a new vector
                  is created.

           vecName expr expression
                  Computes the expression and resets  the  values  of  the  vector
                  accordingly.    Both  scalar  and  vector  math  operations  are
                  allowed.  All values in expressions are either real  numbers  or
                  names of vectors.  All numbers are treated as one component vec-
                  tors.

           vecName length ?newSize?
                  Queries or resets the number of components in vecName.   NewSize
                  is  a  number specifying the new size of the vector.  If newSize
                  is smaller than the current size of vecName,  vecName  is  trun-
                  cated.   If  newSize  is greater, the vector is extended and the
                  new components are initialized to 0.0.  If no  newSize  argument
                  is present, the current length of the vector is returned.

           vecName merge srcName ?srcName?...
                  Merges  the  named  vectors into a single vector.  The resulting
                  vector is formed by merging the components of each source vector
                  one index at a time.

           vecName notify keyword
                  Controls  how vector clients are notified of changes to the vec-
                  tor.  The exact behavior is determined by keyword.

                  always Indicates that clients are  to  be  notified  immediately
                         whenever the vector is updated.

                  never  Indicates that no clients are to be notified.

                  whenidle
                         Indicates  that  clients  are  to be notified at the next
                         idle point whenever the vector is updated.

                  now    If any client notifications is  currently  pending,  they
                         are notified immediately.

                  cancel Cancels  pending  notifications of clients using the vec-
                         tor.

                  density number of new components, whose values are  evenly  dis-
                  tributed between the original components values.  This is useful
                  for generating abscissas to be interpolated along a spline.

           vecName range firstIndex ?lastIndex?...
                  Returns a list of numeric values representing the vector  compo-
                  nents  between  two  indices.  Both firstIndex and lastIndex are
                  indices representing the range of components to be returned.  If
                  lastIndex  is less than firstIndex, the components are listed in
                  reverse order.

           vecName search value ?value?
                  Searches for a value or range of values among the components  of
                  vecName.   If  one value argument is given, a list of indices of
                  the components which equal value is returned.  If a second value
                  is  also  provided, then the indices of all components which lie
                  within the range of the two values are returned.  If  no  compo-
                  nents are found, then "" is returned.

           vecName set item
                  Resets  the components of the vector to item. Item can be either
                  a list of numeric expressions or another vector.

           vecName seq start ?finish? ?step?
                  Generates a sequence of values starting with  the  value  start.
                  Finish  indicates  the  terminating  value of the sequence.  The
                  vector is automatically resized to contain  just  the  sequence.
                  If three arguments are present, step designates the interval.

                  With  only two arguments (no finish argument), the sequence will
                  continue until the vector is filled.   With  one  argument,  the
                  interval defaults to 1.0.

           vecName sort ?-reverse? ?argName?...
                  Sorts  the  vector vecName in increasing order.  If the -reverse
                  flag is present, the vector is sorted in decreasing  order.   If
                  other  arguments argName are present, they are the names of vec-
                  tors which will be rearranged in the  same  manner  as  vecName.
                  Each  vector  must be the same length as vecName.  You could use
                  this to sort the x vector of a graph, while still retaining  the
                  same x,y coordinate pairs in a y vector.

           vecName variable varName
                  Maps  a  Tcl  variable to the vector, creating another means for
                  accessing the vector.  The variable varName can't already exist.
                  This overrides any current variable mapping the vector may have.

## C LANGUAGE API

           You can create, modify, and destroy vectors from C code, using  library
           routines.   You  need to include the header file blt.h. It contains the
           definition of the structure Blt_Vector, which  represents  the  vector.
           It appears below.  typedef struct {
           Blt_CreateVector

             Synopsis: int Blt_CreateVector (interp, vecName, length, vecPtrPtr)
                          Tcl_Interp  *interp; char *vecName; int length; Blt_Vec-
                          tor **vecPtrPtr;

             Description:
                       Creates a new vector  vecName  with  a  length  of  length.
                       Blt_CreateVector  creates  both a new Tcl command and array
                       variable vecName.  Neither a  command  nor  variable  named
                       vecName  can  already  exist.   A  pointer to the vector is
                       placed into vecPtrPtr.

             Results:  Returns TCL_OK if the vector is successfully  created.   If
                       length  is  negative,  a  Tcl  variable  or command vecName
                       already exists, or memory cannot be allocated for the  vec-
                       tor,  then  TCL_ERROR  is  returned and interp->result will
                       contain an error message.

           Blt_DeleteVectorByName

             Synopsis: int Blt_DeleteVectorByName (interp, vecName)
                          Tcl_Interp *interp; char *vecName;

             Description:
                       Removes the vector vecName.  VecName is the name of a  vec-
                       tor  which  must  already  exist.  Both the Tcl command and
                       array variable vecName are destroyed.  All clients  of  the
                       vector  will  be  notified  immediately that the vector has
                       been destroyed.

             Results:  Returns TCL_OK if the vector is successfully  deleted.   If
                       vecName  is  not  the  name  a  vector,  then  TCL_ERROR is
                       returned and interp->result will contain an error  message.

           Blt_DeleteVector

             Synopsis: int Blt_DeleteVector (vecPtr)
                          Blt_Vector *vecPtr;

             Description:
                       Removes  the  vector  pointed  to  by  vecPtr.  VecPtr is a
                       pointer to a vector,  typically  set  by  Blt_GetVector  or
                       Blt_CreateVector.   Both the Tcl command and array variable
                       of the vector are destroyed.  All  clients  of  the  vector
                       will  be  notified  immediately  that  the  vector has been
                       destroyed.

             Results:  Returns TCL_OK if the vector is successfully  deleted.   If
                       vecName  is  not  the  name  a  vector,  then  TCL_ERROR is

             Results:  Returns TCL_OK if the vector is successfully retrieved.  If
                       vecName  is  not  the  name  of a vector, then TCL_ERROR is
                       returned and interp->result will contain an error  message.

           Blt_ResetVector

             Synopsis: int  Blt_ResetVector  (vecPtr,  dataArr,         numValues,
                       arraySize, freeProc)
                          Blt_Vector *vecPtr; double *dataArr; int *numValues; int
                          *arraySize; Tcl_FreeProc *freeProc;

             Description:
                       Resets  the  components of the vector pointed to by vecPtr.
                       Calling Blt_ResetVector will trigger the vector to dispatch
                       notifications  to its clients. DataArr is the array of dou-
                       bles which represents the vector  data.  NumValues  is  the
                       number  of  elements  in the array. ArraySize is the actual
                       size of the array (the array may be bigger than the  number
                       of values stored in it). FreeProc indicates how the storage
                       for the vector component array (dataArr) was allocated.  It
                       is used to determine how to reallocate memory when the vec-
                       tor is resized  or  destroyed.   It  must  be  TCL_DYNAMIC,
                       TCL_STATIC,  TCL_VOLATILE,  or  a  pointer to a function to
                       free the memory allocated for the vector array. If freeProc
                       is  TCL_VOLATILE,  it indicates that dataArr must be copied
                       and saved.  If freeProc is TCL_DYNAMIC, it  indicates  that
                       dataArr  was dynamically allocated and that Tcl should free
                       dataArr if necessary.  Static indicates that nothing should
                       be done to release storage for dataArr.

             Results:  Returns  TCL_OK  if the vector is successfully resized.  If
                       newSize is negative, a vector vecName does  not  exist,  or
                       memory  cannot  be allocated for the vector, then TCL_ERROR
                       is returned and interp->result will contain an  error  mes-
                       sage.

           Blt_ResizeVector

             Synopsis: int Blt_ResizeVector (vecPtr, newSize)
                          Blt_Vector *vecPtr; int newSize;

             Description:
                       Resets  the  length  of  the vector pointed to by vecPtr to
                       newSize.  If newSize is smaller than the  current  size  of
                       the  vector,  it  is truncated.  If newSize is greater, the
                       vector is extended and the new components  are  initialized
                       to 0.0.  Calling Blt_ResetVector will trigger the vector to
                       dispatch notifications.

                Results:  Returns 1 if a vector vecName exists and 0 otherwise.

             If  your  application  needs to be notified when a vector changes, it
             can allocate a unique client identifier for itself.  Using this iden-
             tifier,  you  can  then  register a call-back to be made whenever the
             vector is updated or destroyed.  By default, the call-backs are  made
             at the next idle point.  This can be changed to occur at the time the
             vector is modified.  An application can allocate more than one  iden-
             tifier  for any vector.  When the client application is done with the
             vector, it should free the identifier.

             The call-back routine must of the following type.

                    typedef void (Blt_VectorChangedProc) (Tcl_Interp *interp,
                       ClientData clientData, Blt_VectorNotify notify);

             ClientData is passed to this routine whenever it is called.  You  can
             use  this  to pass information to the call-back.  The notify argument
             indicates whether the vector has been updated of destroyed. It is  an
             enumerated type.

                    typedef enum {
                        BLT_VECTOR_NOTIFY_UPDATE=1,
                        BLT_VECTOR_NOTIFY_DESTROY=2 } Blt_VectorNotify;

             Blt_AllocVectorId

                Synopsis: Blt_VectorId Blt_AllocVectorId (interp, vecName)
                            Tcl_Interp *interp; char *vecName;

                Description:
                          Allocates  an client identifier for with the vector vec-
                          Name.  This identifier can be used to  specify  a  call-
                          back  which  is  triggered when the vector is updated or
                          destroyed.

                Results:  Returns a client identifier if successful.   If  vecName
                          is  not  the name of a vector, then NULL is returned and
                          interp->result will contain an error message.

             Blt_GetVectorById

                Synopsis: int Blt_GetVector (interp, clientId, vecPtrPtr)
                            Tcl_Interp *interp; Blt_VectorId clientId;  Blt_Vector
                            **vecPtrPtr;

                Description:
                          Retrieves  the  vector  used by clientId.  ClientId is a
                          valid   vector   client    identifier    allocated    by
                          Specifies  a call-back routine to be called whenever the
                          vector associated with clientId is updated  or  deleted.
                          Proc  is  a  pointer to call-back routine and must be of
                          the type Blt_VectorChangedProc.  ClientData  is  a  one-
                          word  value  to  be  passed  to  the  routine when it is
                          invoked. If proc is NULL, then the client is  not  noti-
                          fied.

                Results:  The  designated call-back procedure will be invoked when
                          the vector is updated or destroyed.

             Blt_FreeVectorId

                Synopsis: void Blt_FreeVectorId (clientId);
                            Blt_VectorId clientId;

                Description:
                          Frees the client identifier.  Memory allocated  for  the
                          identifier  is  released.   The client will no longer be
                          notified when the vector is modified.

                Results:  The designated call-back procedure will be no longer  be
                          invoked when the vector is updated or destroyed.

             Blt_NameOfVectorId

                Synopsis: char *Blt_NameOfVectorId (clientId);
                            Blt_VectorId clientId;

                Description:
                          Retrieves  the  name  of  the vector associated with the
                          client identifier clientId.

                Results:  Returns the name of the vector associated with clientId.
                          If  clientId is not an identifier or the vector has been
                          destroyed, NULL is returned.

             Blt_InstallIndexProc

                Synopsis: void Blt_InstallIndexProc (indexName, procPtr)
                            char *indexName; Blt_VectorIndexProc *procPtr;

                Description:
                          Registers a function to be called to retrieved the index
                          indexName from the vector's array variable.

                          typedef double Blt_VectorIndexProc(Vector *vecPtr);

                          The  function  will  be  passed a pointer to the vector.

           reset  shortly.  The  vector  is updated when lt_ResetVector is called.
           Blt_ResetVector makes the changes visible  to  the  Tcl  interface  and
           other vector clients (such as a graph widget).

           #include  <tcl.h>  #include  <blt.h>         Blt_Vector *vecPtr; double
           *newArr; FILE *f; struct stat statBuf; int numBytes, numValues;

           f = fopen("binary.dat", "r"); fstat(fileno(f),  &statBuf);  numBytes  =
           (int)statBuf.st_size;

           /*  Allocate an array big enough to hold all the data */ newArr = (dou-
           ble  *)malloc(numBytes);  numValues  =   numBytes   /   sizeof(double);
           fread((void *)newArr, numValues, sizeof(double), f); fclose(f);

           if (Blt_VectorExists(interp, "data"))  {
               if   (Blt_GetVector(interp,   "data",   &vecPtr)   !=   TCL_OK)   {
                   return TCL_ERROR;
               } } else {
              if  (Blt_CreateVector(interp,  "data",  0,  &vecPtr)  !=  TCL_OK)  {
                   return TCL_ERROR;
              } } /*
            * Reset the vector. Clients will be notified when Tk is idle.
            * TCL_DYNAMIC tells the vector to free the memory allocated
            * if it needs to reallocate or destroy the vector.
            */   if   (Blt_ResetVector(vecPtr,   newArr,   numValues,   numValues,
                   TCL_DYNAMIC) != TCL_OK) {
               return TCL_ERROR; }

## INCOMPATIBILITIES

           In previous versions, if the array variable isn't global (i.e. local to
           a Tcl procedure), the vector is automatically destroyed when the proce-
           dure returns.  proc doit {} {
               # Temporary vector x
               vector x(10)
               set x(9) 2.0
                 ...  }

           This has changed.  Variables are not automatically destroyed when their
           variable  is  unset.   You  can restore the old behavior by setting the
           "-watchunset" switch.

## KEYWORDS

           vector, graph, widget

    BLT                               BLT_VERSION                   blt::vector(n)