modifing a jet-LUT to colour only the value 0 in white

[lynx . abraxas]

Hello!


How  can  I  use  pcolor (for plotting 2D-histograms) such that only the value
zero is plotted in white and all other values according to a lut (eg jet)?

If I do:

cmap= jet(N);

cmap(1,:)=[1,1,1];
or
cmap=vertcat([1,1,1],cmap);

pcolor is colouring also some small values (eg. 0.001, depending on N) above 0
with white.
How could I make the range that is coloured with white end at exactly 0?


Many thanks for any help or hints
Lynx