I often have large matrices and have to grab only every nth column or row (for plotting

for example). So far I've been doing it this way:

nthColumns:=proc(v_m, v_n)  

v_m[..,[seq(i, i=1..rtable_size(v_m)[2], v_n)]]

end;

nthRows:=proc(v_m, v_n) 

 v_m[[seq(i, i=1..rtable_size(v_m)[1], v_n)],..]

end;

A := LinearAlgebra:-RandomMatrix(20, 20, outputoptions = [datatype = float[8]]);

I often have to create density plots with many (thousands of) points. Hence the first thing I do when I install a new version of maple on linux, is edit dir_of_maple/bin/maple so that

JAVAHEAP=512

is instead

JAVAHEAP=4096

I have done this for years and never have any memory problems. But recently I have sent my code to someone who runs Windows and they seem to have "out of memory" issues when trying to do density plots of large datasets.

From the page:

http://www.maplesoft.com/products/system_requirements.aspx

it would seem like ubuntu 12.04 is not officially supported for Maple 16. Could someone from Maplesoft comment if there are plans to add support with perhaps a patch? or will we have to wait until Maple 17?

I need to update for certain sofware, but would want to make sure I can run maple in an uncompromised way.

thanks

Hi:

i am trying to pick off some terms programatically from a list of expressions/equations, and am having some trouble.

consider:

> select(has, y+3*x(t), x); # works
                                               ...

Hi:

I am having trouble with the Physics[diff] operator.

restart:
with(Physics):

#Setup noncommutative operators:
Setup(noncommutativeprefix = {P, H, rho});
              [noncommutativeprefix = {H, P, rho}]

#this works:
diff(P(t),t);
                    
#even more complicated stuff works: