cold-to-hot color ramp

num = 64;
v = linspace(-1,1,num);

if true
    h = linspace(2/3,0,num)';
    clr = hsv2rgb([h ones(num,2)]);
else
    clr = flipud(hsv(num));
end

figure
subplot(4,1,1), imagesc(v), colormap(clr), axis off, title('hsv')
subplot(4,1,2:4), h = plot(v,clr); axis tight
set(h(1), 'Color','r', 'LineWidth',3)
set(h(2), 'Color','g', 'LineWidth',3)
set(h(3), 'Color','b', 'LineWidth',3)