`plscmap1a`: Set semitransparent cmap1 RGBA colors.
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#### `plscmap1a`: Set semitransparent cmap1 RGBA colors.

`plscmap1a (` | r ,
| g ,
| b ,
| alpha ,
| ncol1 `)`;

Set semitransparent cmap1 colors (see the section called “Color Map1”) using RGBA vector values. This function also sets the number of cmap1 colors. N.B. Continuous cmap1 colors are indexed with a floating-point index in the range from 0.0-1.0 which is linearly transformed (e.g., by `plcol1`) to an integer index of these RGBA vectors in the range from 0 to `ncol1-1`. So in order for this continuous color model to work properly, it is the responsibility of the user of `plscmap1` to insure that these RGBA vectors are continuous functions of their integer indices.

`r` (``PLINT_VECTOR``, input)

  A vector that represents (using unsigned 8-bit integers in the range from 0-255) the degree of red in the color as a continuous function of the integer index of the vector.

`g` (``PLINT_VECTOR``, input)

  A vector that represents (using unsigned 8-bit integers in the range from 0-255) the degree of green in the color as a continuous function of the integer index of the vector.

`b` (``PLINT_VECTOR``, input)

  A vector that represents (using unsigned 8-bit integers in the range from 0-255) the degree of blue in the color as a continuous function of the integer index of the vector.

`alpha` (``PLFLT_VECTOR``, input)

  A vector that represents (using PLFLT values in the range from 0.0-1.0 where 0.0 corresponds to completely transparent and 1.0 corresponds to completely opaque) the alpha transparency of the color as a continuous function of the integer index of the vector.

`ncol1` (``PLINT``, input)

  Number of items in the ``r`` , ``g`` , ``b`` , and ``alpha`` vectors.

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

This function is used in example 31.

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