STScI Logo

mkfunc stsdas.sobsolete



mkfunc -- Make a file containing functional form data and proper FITS coordinates.


mkfunc output function npts shift


This task lets the user specify a function name (the same functions as used in the testfunc task), a number of data points, and the origin offset from the first pixel. From this a file is built that contains data from the function.


output [file]
Name of output image.
function [string]
[Allowed values: bessel | constant | delta | gaussian | heaviside | pe | po | box | rectangle | signum | comb | shah | sinc | sine | cosine | triangle | y | line]
Name of the function to be used. The following table shows the supported functions, which are described in Bracewell's book "The Fourier Transform and Its Applications."

Value             Function
=====             ========
bessel            Bessel function ('J0')
box               Bracewell's box function
comb              Dirac comb, Bracewell shah
constant          Constant
cosine            cosine
delta             Delta function
gaussian          Gaussian
heaviside         Heaviside unit step
line              Unit-slope line
pe                Even impulse pair
po                Odd impulse pair
rectangle         Bracewell's box function
shah              Dirac comb, Bracewell shah
signum            sign (x)
sinc              sin (pi x) / (pi x)
sine              sine
triangle          Bracewell's wedge function
y                 Unit-slope line

npts = [integer, min=1]
Number of points.
shift = [integer]
Shift origin (in pixels).
(constant = 1.0) [real]
Value of the constant function.
(fcw = 10.0) [real, min=1.0]
Characteristic width of the function.

The bold and inquisitive user may also adjust the "characteristic width" of the function, which may have different meanings for different functions. For things like the boxcar or Gaussian functions, the notion of width is pretty intuitive; for things like the impulse pairs function, it represents the separation of the pulses. "Characteristic width" is meaningless for things like a delta function or a step function.


1. Use mkfunc to create a file called cos.hhh. Use the cosine function with 100 data points.

  fo> mkfunc cos.hhh cosine 100 0



bracewell, testfunc

Type "help fourier option=sys" for a higher-level description of the fourier package.

Source Code · Package Help · Search Form · STSDAS