int im_sines(image, xsize, ysize, horfreq, verfreq) IMAGE *image; int xsize, ysize; double horfreq, verfreq;
creates a float one band image of the a sine waveform in two dimensions.
The sizes of the created image are xsize by ysize. The number of
horizontal and vertical spatial frequencies are determined by the variables
horfreq and verfreq respectively. The function is the base for creating
displayable sine waves and square waves in two dimensions.
The function returns 0 on success and -1 on error.