[Gnuplot-info] map view of data matrix with block structure

[Michael L. <M_L...@ho...>]

Hello,

I'm making an image plot ('set view map') of a 27x27 correlation
matrix that has a block diagonal structure. The [1:18,1:18] 
top-left submatrix and the [19:27,19:27] lower-right submatrix are
all positive and closer to +1; the off-diagonal submatricies 
are all negative and closer to -1.  My problem is that on
the boundary gnuplot is interpolating and plotting a 
color that indicates it is near zero. What I want is 
a sharp distinction between the boundaries but nice
color gradients in each submatrix showing the transition
towards +/- 1.  Any help would be much appreciated.

Here's what I've done so far
---
set pm3d
set view map
set size square
set palette model RGB
set noxtics
set noytics

set palette defined (my nice blue to red pallette choice)

splot "cormatrix" matrix with pm3d # for example

set xrange [] reverse
set yrange [] reverse
replot
---

Thanks,
Mike