man plscmap1a (3): Set cmap1 colors using 8-bit RGB values and double alpha transparency values

SYNOPSIS

plscmap1a(r, g, b, alpha, ncol1)

Set cmap1 colors using 8-bit RGB values (see the PLplot documentation) and double alpha transparency values. This also sets the number of colors.

Redacted form: plscmap1a(r, g, b, alpha)

This function is used in example 31.

r (const PLINT *, input): Pointer to array with set of unsigned 8-bit integers (0-255) representing the degree of red in the color.
g (const PLINT *, input): Pointer to array with set of unsigned 8-bit integers (0-255) representing the degree of green in the color.
b (const PLINT *, input): Pointer to array with set of unsigned 8-bit integers (0-255) representing the degree of blue in the color.
alpha (const PLFLT *, input): Pointer to array with set of double values (0.0-1.0) representing the alpha transparency value of the color.
ncol1 (PLINT, input): Number of items in the r, g, b, and alpha arrays.

Many developers (who are credited at http://plplot.sourceforge.net/credits.php) have contributed to PLplot over its long history.