.TH PLTF 1 "17 October 2003" "plt 2.3" "WFDB Applications Guide"
.SH NAME
pltf \- make function plots
.SH SYNOPSIS
\fBpltf\fR [ \fIexpression\fR [ \fIxmin\fR [ \fIxmax\fR [ \fIxinc\fR ] ] ] ]
.SH DESCRIPTION
.PP
\fBpltf\fR provides a simple way to use \fBbc\fR(1) and \fBplt\fR(1)
to generate plots of many common functions of a single variable.  The
command-line arguments are interpreted according to their position;
\fBpltf\fR asks for values for any missing arguments.
.PP
The first argument, \fIexpression\fR, can be any expression valid as input
to \fBbc\fR(1), with the additional feature that the variable \fBx\fR may
appear anywhere in the expression where a number would be allowed by \fBbc\fR.
Some examples of valid expressions are:
.IP
\fBx^3+3*x^2+3*x+1\fR
.IP
\fB(x + 1)^3\fR
.IP
\fBs(sqrt(x^2))\fR
.PP
The first two of these are equivalent;  note that whitespace and parentheses
are allowed in expressions, although it is necessary to enclose such
expressions in double quotes (e.g., \fB"(x + 1)*e(x)"\fR) when entering them as
command-line arguments in order to protect them from the shell.  The
last expression is the sine of the square root of x squared;  see \fBbc\fR(1)
for a complete list of available special functions, or invoke \fBpltf\fR
with no command-line arguments to obtain a list.
.PP
The second and third arguments specify the domain of the function (the
values over which \fBx\fR should vary), and the fourth argument specifies the
\fBx\fR-increment (the difference between consecutive values of \fBx\fR for
which the expression is to be evaluated).
.PP
\fBpltf\fR is a shell script that uses a helper application, \fBftable\fR, to
prepare input for \fBbc -l\fR.  Invoke \fBftable\fR directly (using the same
arguments as for \fBpltf\fR) if you need to change the format of the plot
or make a printed version of it.  See the source for \fBpltf\fR to see how to
do this.
.SH SEE ALSO
.PP
\fBimageplt\fR(1), \fBplt\fR(1)
.SH AVAILABILITY
\fBpltf\fR is available as part of the \fBplt\fR package in
PhysioToolkit (see \fBSOURCES\fR below) under the GPL.
.SH AUTHOR
George B. Moody (\fBgeorge@mit.edu\fR)
.SH SOURCES
.PP
\fBhttp://www.physionet.org/physiotools/plt/plt/misc/pltf\fR
.PP
\fBhttp://www.physionet.org/physiotools/plt/plt/misc/ftable.c\fR