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/*****************************************************************************
*                                                                            *
*   INFERNO.SPL  Copyright (C) 2021 DSP Development Corporation              *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    Generate a colormap of blue, green, yellow                  *
*                                                                            *
*   Revisions:   30 Mar 2021  RRR  Creation                                  *
*                                                                            *
*****************************************************************************/


#if @HELP_INFERNO

    INFERNO

    Purpose: Generates a colormap of magenta, red, yellow.

    Syntax:  INFERNO(len)

               len - optional colormap length, defaults to
                     the length of the current colormap


    Returns: A table of RGB triples suitable for the SETCOLORMAP function.

    Example:
             clen = length(getcolormap());
             density(ravel(rep(0..(clen-1), 32), clen)');
             inferno;

             Creates a table of 32 x colormap length RBG values and
             displays the resulting colors. The resulting image is a
             vertical plot of colors ranging from magenta (lowest) to
             red to yellow (highest).

    Example:
             inferno(256);showcmap

             Creates a table of 32 x 256 length RBG values and
             displays the resulting colors. The resulting image is a
             vertical plot of colors ranging from blue (lowest) to
             green to yellow (highest).

    Remarks:
             INFERNO() by itself sets the colormap and shading.

             a = inferno() or setcolormap(inferno()) returns the rgb values.
             In this case, use SETSHADING to make the new colormap
             take effect on an existing density or 2D plot.

             The colormap is meant do provide better color separation for
             viewers with some forms of color blindness.

    See Also:
             Autumn
             Bone
             Cool
             Copper
             Gray
             Hot
             Hsv
             Pink
             Rainbow
             Setcolormap
             Setshading
             Showcmap
             Spring
             Summer
             Winter
#endif


/* inferno colormap */
inferno(cmaplen)
{
        local rgb, rgblen;

        if (argc < 1)
        {
                cmaplen = length(getcolormap());
        }

        /* RGB colors */
        rgb =
        {
                { 0.001462, 0.000466, 0.013866 },
                { 0.002267, 0.001270, 0.018570 },
                { 0.003299, 0.002249, 0.024239 },
                { 0.004547, 0.003392, 0.030909 },
                { 0.006006, 0.004692, 0.038558 },
                { 0.007676, 0.006136, 0.046836 },
                { 0.009561, 0.007713, 0.055143 },
                { 0.011663, 0.009417, 0.063460 },
                { 0.013995, 0.011225, 0.071862 },
                { 0.016561, 0.013136, 0.080282 },
                { 0.019373, 0.015133, 0.088767 },
                { 0.022447, 0.017199, 0.097327 },
                { 0.025793, 0.019331, 0.105930 },
                { 0.029432, 0.021503, 0.114621 },
                { 0.033385, 0.023702, 0.123397 },
                { 0.037668, 0.025921, 0.132232 },
                { 0.042253, 0.028139, 0.141141 },
                { 0.046915, 0.030324, 0.150164 },
                { 0.051644, 0.032474, 0.159254 },
                { 0.056449, 0.034569, 0.168414 },
                { 0.061340, 0.036590, 0.177642 },
                { 0.066331, 0.038504, 0.186962 },
                { 0.071429, 0.040294, 0.196354 },
                { 0.076637, 0.041905, 0.205799 },
                { 0.081962, 0.043328, 0.215289 },
                { 0.087411, 0.044556, 0.224813 },
                { 0.092990, 0.045583, 0.234358 },
                { 0.098702, 0.046402, 0.243904 },
                { 0.104551, 0.047008, 0.253430 },
                { 0.110536, 0.047399, 0.262912 },
                { 0.116656, 0.047574, 0.272321 },
                { 0.122908, 0.047536, 0.281624 },
                { 0.129285, 0.047293, 0.290788 },
                { 0.135778, 0.046856, 0.299776 },
                { 0.142378, 0.046242, 0.308553 },
                { 0.149073, 0.045468, 0.317085 },
                { 0.155850, 0.044559, 0.325338 },
                { 0.162689, 0.043554, 0.333277 },
                { 0.169575, 0.042489, 0.340874 },
                { 0.176493, 0.041402, 0.348111 },
                { 0.183429, 0.040329, 0.354971 },
                { 0.190367, 0.039309, 0.361447 },
                { 0.197297, 0.038400, 0.367535 },
                { 0.204209, 0.037632, 0.373238 },
                { 0.211095, 0.037030, 0.378563 },
                { 0.217949, 0.036615, 0.383522 },
                { 0.224763, 0.036405, 0.388129 },
                { 0.231538, 0.036405, 0.392400 },
                { 0.238273, 0.036621, 0.396353 },
                { 0.244967, 0.037055, 0.400007 },
                { 0.251620, 0.037705, 0.403378 },
                { 0.258234, 0.038571, 0.406485 },
                { 0.264810, 0.039647, 0.409345 },
                { 0.271347, 0.040922, 0.411976 },
                { 0.277850, 0.042353, 0.414392 },
                { 0.284321, 0.043933, 0.416608 },
                { 0.290763, 0.045644, 0.418637 },
                { 0.297178, 0.047470, 0.420491 },
                { 0.303568, 0.049396, 0.422182 },
                { 0.309935, 0.051407, 0.423721 },
                { 0.316282, 0.053490, 0.425116 },
                { 0.322610, 0.055634, 0.426377 },
                { 0.328921, 0.057827, 0.427511 },
                { 0.335217, 0.060060, 0.428524 },
                { 0.341500, 0.062325, 0.429425 },
                { 0.347771, 0.064616, 0.430217 },
                { 0.354032, 0.066925, 0.430906 },
                { 0.360284, 0.069247, 0.431497 },
                { 0.366529, 0.071579, 0.431994 },
                { 0.372768, 0.073915, 0.432400 },
                { 0.379001, 0.076253, 0.432719 },
                { 0.385228, 0.078591, 0.432955 },
                { 0.391453, 0.080927, 0.433109 },
                { 0.397674, 0.083257, 0.433183 },
                { 0.403894, 0.085580, 0.433179 },
                { 0.410113, 0.087896, 0.433098 },
                { 0.416331, 0.090203, 0.432943 },
                { 0.422549, 0.092501, 0.432714 },
                { 0.428768, 0.094790, 0.432412 },
                { 0.434987, 0.097069, 0.432039 },
                { 0.441207, 0.099338, 0.431594 },
                { 0.447428, 0.101597, 0.431080 },
                { 0.453651, 0.103848, 0.430498 },
                { 0.459875, 0.106089, 0.429846 },
                { 0.466100, 0.108322, 0.429125 },
                { 0.472328, 0.110547, 0.428334 },
                { 0.478558, 0.112764, 0.427475 },
                { 0.484789, 0.114974, 0.426548 },
                { 0.491022, 0.117179, 0.425552 },
                { 0.497257, 0.119379, 0.424488 },
                { 0.503493, 0.121575, 0.423356 },
                { 0.509730, 0.123769, 0.422156 },
                { 0.515967, 0.125960, 0.420887 },
                { 0.522206, 0.128150, 0.419549 },
                { 0.528444, 0.130341, 0.418142 },
                { 0.534683, 0.132534, 0.416667 },
                { 0.540920, 0.134729, 0.415123 },
                { 0.547157, 0.136929, 0.413511 },
                { 0.553392, 0.139134, 0.411829 },
                { 0.559624, 0.141346, 0.410078 },
                { 0.565854, 0.143567, 0.408258 },
                { 0.572081, 0.145797, 0.406369 },
                { 0.578304, 0.148039, 0.404411 },
                { 0.584521, 0.150294, 0.402385 },
                { 0.590734, 0.152563, 0.400290 },
                { 0.596940, 0.154848, 0.398125 },
                { 0.603139, 0.157151, 0.395891 },
                { 0.609330, 0.159474, 0.393589 },
                { 0.615513, 0.161817, 0.391219 },
                { 0.621685, 0.164184, 0.388781 },
                { 0.627847, 0.166575, 0.386276 },
                { 0.633998, 0.168992, 0.383704 },
                { 0.640135, 0.171438, 0.381065 },
                { 0.646260, 0.173914, 0.378359 },
                { 0.652369, 0.176421, 0.375586 },
                { 0.658463, 0.178962, 0.372748 },
                { 0.664540, 0.181539, 0.369846 },
                { 0.670599, 0.184153, 0.366879 },
                { 0.676638, 0.186807, 0.363849 },
                { 0.682656, 0.189501, 0.360757 },
                { 0.688653, 0.192239, 0.357603 },
                { 0.694627, 0.195021, 0.354388 },
                { 0.700576, 0.197851, 0.351113 },
                { 0.706500, 0.200728, 0.347777 },
                { 0.712396, 0.203656, 0.344383 },
                { 0.718264, 0.206636, 0.340931 },
                { 0.724103, 0.209670, 0.337424 },
                { 0.729909, 0.212759, 0.333861 },
                { 0.735683, 0.215906, 0.330245 },
                { 0.741423, 0.219112, 0.326576 },
                { 0.747127, 0.222378, 0.322856 },
                { 0.752794, 0.225706, 0.319085 },
                { 0.758422, 0.229097, 0.315266 },
                { 0.764010, 0.232554, 0.311399 },
                { 0.769556, 0.236077, 0.307485 },
                { 0.775059, 0.239667, 0.303526 },
                { 0.780517, 0.243327, 0.299523 },
                { 0.785929, 0.247056, 0.295477 },
                { 0.791293, 0.250856, 0.291390 },
                { 0.796607, 0.254728, 0.287264 },
                { 0.801871, 0.258674, 0.283099 },
                { 0.807082, 0.262692, 0.278898 },
                { 0.812239, 0.266786, 0.274661 },
                { 0.817341, 0.270954, 0.270390 },
                { 0.822386, 0.275197, 0.266085 },
                { 0.827372, 0.279517, 0.261750 },
                { 0.832299, 0.283913, 0.257383 },
                { 0.837165, 0.288385, 0.252988 },
                { 0.841969, 0.292933, 0.248564 },
                { 0.846709, 0.297559, 0.244113 },
                { 0.851384, 0.302260, 0.239636 },
                { 0.855992, 0.307038, 0.235133 },
                { 0.860533, 0.311892, 0.230606 },
                { 0.865006, 0.316822, 0.226055 },
                { 0.869409, 0.321827, 0.221482 },
                { 0.873741, 0.326906, 0.216886 },
                { 0.878001, 0.332060, 0.212268 },
                { 0.882188, 0.337287, 0.207628 },
                { 0.886302, 0.342586, 0.202968 },
                { 0.890341, 0.347957, 0.198286 },
                { 0.894305, 0.353399, 0.193584 },
                { 0.898192, 0.358911, 0.188860 },
                { 0.902003, 0.364492, 0.184116 },
                { 0.905735, 0.370140, 0.179350 },
                { 0.909390, 0.375856, 0.174563 },
                { 0.912966, 0.381636, 0.169755 },
                { 0.916462, 0.387481, 0.164924 },
                { 0.919879, 0.393389, 0.160070 },
                { 0.923215, 0.399359, 0.155193 },
                { 0.926470, 0.405389, 0.150292 },
                { 0.929644, 0.411479, 0.145367 },
                { 0.932737, 0.417627, 0.140417 },
                { 0.935747, 0.423831, 0.135440 },
                { 0.938675, 0.430091, 0.130438 },
                { 0.941521, 0.436405, 0.125409 },
                { 0.944285, 0.442772, 0.120354 },
                { 0.946965, 0.449191, 0.115272 },
                { 0.949562, 0.455660, 0.110164 },
                { 0.952075, 0.462178, 0.105031 },
                { 0.954506, 0.468744, 0.099874 },
                { 0.956852, 0.475356, 0.094695 },
                { 0.959114, 0.482014, 0.089499 },
                { 0.961293, 0.488716, 0.084289 },
                { 0.963387, 0.495462, 0.079073 },
                { 0.965397, 0.502249, 0.073859 },
                { 0.967322, 0.509078, 0.068659 },
                { 0.969163, 0.515946, 0.063488 },
                { 0.970919, 0.522853, 0.058367 },
                { 0.972590, 0.529798, 0.053324 },
                { 0.974176, 0.536780, 0.048392 },
                { 0.975677, 0.543798, 0.043618 },
                { 0.977092, 0.550850, 0.039050 },
                { 0.978422, 0.557937, 0.034931 },
                { 0.979666, 0.565057, 0.031409 },
                { 0.980824, 0.572209, 0.028508 },
                { 0.981895, 0.579392, 0.026250 },
                { 0.982881, 0.586606, 0.024661 },
                { 0.983779, 0.593849, 0.023770 },
                { 0.984591, 0.601122, 0.023606 },
                { 0.985315, 0.608422, 0.024202 },
                { 0.985952, 0.615750, 0.025592 },
                { 0.986502, 0.623105, 0.027814 },
                { 0.986964, 0.630485, 0.030908 },
                { 0.987337, 0.637890, 0.034916 },
                { 0.987622, 0.645320, 0.039886 },
                { 0.987819, 0.652773, 0.045581 },
                { 0.987926, 0.660250, 0.051750 },
                { 0.987945, 0.667748, 0.058329 },
                { 0.987874, 0.675267, 0.065257 },
                { 0.987714, 0.682807, 0.072489 },
                { 0.987464, 0.690366, 0.079990 },
                { 0.987124, 0.697944, 0.087731 },
                { 0.986694, 0.705540, 0.095694 },
                { 0.986175, 0.713153, 0.103863 },
                { 0.985566, 0.720782, 0.112229 },
                { 0.984865, 0.728427, 0.120785 },
                { 0.984075, 0.736087, 0.129527 },
                { 0.983196, 0.743758, 0.138453 },
                { 0.982228, 0.751442, 0.147565 },
                { 0.981173, 0.759135, 0.156863 },
                { 0.980032, 0.766837, 0.166353 },
                { 0.978806, 0.774545, 0.176037 },
                { 0.977497, 0.782258, 0.185923 },
                { 0.976108, 0.789974, 0.196018 },
                { 0.974638, 0.797692, 0.206332 },
                { 0.973088, 0.805409, 0.216877 },
                { 0.971468, 0.813122, 0.227658 },
                { 0.969783, 0.820825, 0.238686 },
                { 0.968041, 0.828515, 0.249972 },
                { 0.966243, 0.836191, 0.261534 },
                { 0.964394, 0.843848, 0.273391 },
                { 0.962517, 0.851476, 0.285546 },
                { 0.960626, 0.859069, 0.298010 },
                { 0.958720, 0.866624, 0.310820 },
                { 0.956834, 0.874129, 0.323974 },
                { 0.954997, 0.881569, 0.337475 },
                { 0.953215, 0.888942, 0.351369 },
                { 0.951546, 0.896226, 0.365627 },
                { 0.950018, 0.903409, 0.380271 },
                { 0.948683, 0.910473, 0.395289 },
                { 0.947594, 0.917399, 0.410665 },
                { 0.946809, 0.924168, 0.426373 },
                { 0.946392, 0.930761, 0.442367 },
                { 0.946403, 0.937159, 0.458592 },
                { 0.946903, 0.943348, 0.474970 },
                { 0.947937, 0.949318, 0.491426 },
                { 0.949545, 0.955063, 0.507860 },
                { 0.951740, 0.960587, 0.524203 },
                { 0.954529, 0.965896, 0.540361 },
                { 0.957896, 0.971003, 0.556275 },
                { 0.961812, 0.975924, 0.571925 },
                { 0.966249, 0.980678, 0.587206 },
                { 0.971162, 0.985282, 0.602154 },
                { 0.976511, 0.989753, 0.616760 },
                { 0.982257, 0.994109, 0.631017 },
                { 0.988362, 0.998364, 0.644924 }
        };

        if ((rgblen = length(rgb)) != cmaplen)
        {
                /* interpolate to colormap size */
                rgb = xylookup(1..rgblen, rgb, linspace(1, rgblen, cmaplen));

                /* remove X columns */
                rgb = rgb[.., 1..2..6];
        }

        if (outargc == 0)
        {
                /* set the colormap and shading */
                setplotshading(rgb);
        }
        else
        {
                /* return the colormap */
                setrgbprops(rgb);

                return(rgb);
        }
}