!set methtit=Rewrite an equation
!set methenv=ZZ QQ RR CC
!set methparmtype=parm equation, function, choice, function
!set methhelp=You can use this method to transform an existing equation\
 into an equivalent one, by a composition of addition of terms,\
 exchange of sides and multiplication by a non-zero constant.

!if $wims_read_parm iswordof form check
  !goto $wims_read_parm
!endif

!exit
:form
Rewrite the equation
!read deduc/methparm.phtml 1
$ to <br>
<input size="15" name="methparm2" value="$methparm2">
=
<input size="15" name="methparm4" value="$methparm4">
!set methremark=Your new equation must be equivalent to the original one.
!exit
:check
!distribute items $methparmobj1 into data,left1,sign1,right1
sign2==
sign3==
!if $sign2 notsametext $sign1 and $sign3 notsametext $sign1
  :badequiv
  error=Your new equation is not equivalent to the original one!
  !advance penalty
  !exit
!endif

check1=($left1) - ($right1)
check2=($methparm2) - ($methparm4)

!read deduc/sub/checkzero $check1\
	$check2
!distribute line $out into out1, out2
!read deduc/sub/_Simplify ($check1) / ($check2)
out3=$out
!if $out1=yes or $out2=yes
  !if $out1!=yes or $out2!=yes
    !goto badequiv
  !endif
!else
  out3=$[$out3]
  !if NaN isin $out3 or Inf isin $out3
    !goto badequiv
  !endif
!endif
methexp=Rewriting of \($left1 = $right1)

newobject1=$methparm2 = $methparm4
oldobject=1

!exit
