[GRASS-dev] graph function input limitations

[Paulo van Breugel]

Hi

I am working with the r.mapcalc graph function. When the input (number 
of xy pairs) is very high, I am getting an error message:

"memory exhausted
Parse error
ERROR: parse error"

The largest possible number of xy pairs seems to be somewhere between 
2400 and 2500. It runs with 2400 xy pairs, and pretty fast for that 
matter. Memory usage doesn't go beyond 1.5GB with 2400 xy pairs, while I 
have 12GB RAM (on 64bit Linux computer), so I guess RAM isn't the 
limitation here.

In the help page of r.series, there is a mention of a soft limit of 1024 
files. Does something similar apply here (but with different numbers)?

I can actually work around it, using a approximation of the graph 
function, but would like to know at what number of xy pairs I should 
apply the workaround. Particularly important, is the limit the same for 
all users, or if not, what would be a safe limit? Or is there a way to 
set this limit from within a script?

Cheers,

Paulo
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