PLT(1)

NAME
pltf - make function plots

SYNOPSIS
pltf [ expression [ xmin [ xmax [ xinc ] ] ] ]

DESCRIPTION

pltf provides a simple way to use bc(1) and plt(1) to generate plots of many common functions of a single variable. The command-line arguments are interpreted according to their position; pltf asks for values for any missing arguments.

The first argument, expression, can be any expression valid as input to bc(1), with the additional feature that the variable x may appear anywhere in the expression where a number would be allowed by bc. Some examples of valid expressions are:

    x^3+3*x^2+3*x+1

    (x + 1)^3

    s(sqrt(x^2))

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., "(x + 1)*e(x)") 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 bc(1) for a complete list of available special functions, or invoke pltf with no command-line arguments to obtain a list.

The second and third arguments specify the domain of the function (the values over which x should vary), and the fourth argument specifies the x-increment (the difference between consecutive values of x for which the expression is to be evaluated).

pltf is a shell script that uses a helper application, ftable, to prepare input for bc -l. Invoke ftable directly (using the same arguments as for pltf) if you need to change the format of the plot or make a printed version of it. See the source for pltf to see how to do this.

SEE ALSO

imageplt(1), plt(1)

AVAILABILITY
pltf is available as part of the plt package in PhysioToolkit (see SOURCES below) under the GPL.

AUTHOR
George B. Moody (george@mit.edu)

SOURCES

http://www.physionet.org/physiotools/plt/misc/pltf

http://www.physionet.org/physiotools/plt/misc/ftable.c