.TH DERIVATIVE 1carl CARL
.SH NAME
derivative \- produce (approximation to) derivative of floatsam function
.SH SYNOPSIS
.B derivative 
< floatsams > text or floatsams
.SH DESCRIPTION
.B derivative
reads floatsams from its standard input and produces the signal
.IP
output[n] = input[n] - input[n-1] 
.LP
on its standard output in text format (if talking to a terminal) or
as more floatsams (if looking at a file or pipe).  The output is
a good approximation to the derivative of the input except at high
frequencies.
.SH AUTHOR
Gareth Loy
.SH BUGS
It necessarily writes one less sample than it reads.
