Subtract two surfaces

[Markus Küster]

Hi,
i would like to import two CSV files. So far so good.
This works very well. But I would like to subtract the two surfaces and get the difference (distance) between the two surfaces.

I searched on Google and read a lot of tutorials. But i did not find the right one.
For reading the data and plot it following code is used:

cd 'd:\temp\ '
set datafile separator ";"
set datafile commentschars "#!%"
set dgrid3d splines
set dgrid3d 30,30 qnorm 2
set pm3d
set contour base
set cntrparam levels incr 85,1,95
set cntrlabel start 2 font ",7"
set contour both
set zrange [85:94]
set view 0,0
set palette rgbformulae 22,13,-31
splot "Alt_220_RL_50C.csv" u 1:2:3 with lines,"220_RL_50C.csv" u 1:2:3 with lines

I would like to subtract the two plotted surfaces. For the values that are not available i would try an "if then" solution.
What would be the best way to solve the issue ? I am very happy about every hint and answer i will get.

Best Regards
Markus

[Karl Ratzsch]

(all values will be available, that's what dgrid3d is for.)

Not possible without external help, i'm afraid.

You can plot the two grids to temporary files, combine them (e.g. on unixoid systems paste file1 file2 > nfile)

and then plot that file with

unset dgrid3d
splot nfile using 1:2:($6-$3)