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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Filename: mymap.m
%%
%% Project: A Wishbone Controlled PWM (audio) controller
%%
%% Purpose: This file generates my favorite spectrogram color map. The map
%% is designed so that zero maps to black, and one maps to white.
%% In between the two extremes, the color goes from black to blue, red,
%% orange, yellow, and then white.
%%
%% The one argument given to the colormap is the number of colors
%% you would like to have in your map. 64 is often sufficient.
%%
%% Creator: Dan Gisselquist, Ph.D.
%% Gisselquist Technology, LLC
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Copyright (C) 2017, Gisselquist Technology, LLC
%%
%% This program is free software (firmware): you can redistribute it and/or
%% modify it under the terms of the GNU General Public License as published
%% by the Free Software Foundation, either version 3 of the License, or (at
%% your option) any later version.
%%
%% This program is distributed in the hope that it will be useful, but WITHOUT
%% ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
%% FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
%% for more details.
%%
%% You should have received a copy of the GNU General Public License along
%% with this program. (It's in the $(ROOT)/doc directory. Run make with no
%% target there if the PDF file isn't present.) If not, see
%% <http://www.gnu.org/licenses/> for a copy.
%%
%% License: GPL, v3, as defined and found on www.gnu.org,
%% http://www.gnu.org/licenses/gpl.html
%%
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%%
function [map] = mymap(nclrs)
map = zeros(nclrs,3);
idx = ((1:nclrs)-1)/(nclrs-1);
map(:,1) = 1 - cos((idx-1/3)*3*pi)';
map((idx<1/3),1) = 0;
map((idx>2/3),1) = 1;
map(:,2) = 1 - cos((idx-2/3)*3*pi)';
map(idx<2/3,2) = 0;
map(:,3) = 0.5 * (1-cos(idx*3*pi))';
map((idx<5/6)&(idx>=2/3),3) = 0;
map((idx>=5/6),3) = 1-cos((idx(idx>=5/6)-2/3)*1.5*pi)';
map(map>1.0) = 1.0;
map(map<0.0) = 0.0;