[Israel.pm] PDL - simple vector and matrix operation

Gabor Szabo szabgab at gmail.com
Wed Nov 11 00:07:00 PST 2009


I am still not sure where *I* might need to use PDL but it
is still fun to play with it. It has a command line utility in
which I can play with it interactively.

Let's see an example:

perldl> $x = pdl(1,2,3,4)

perldl> p $x
[1 2 3 4]

perldl> p $x + 1               # add one to each value
[2 3 4 5]

perldl> p $x + $x             # add the values pair wise
[2 4 6 8]
perldl> p $x * $x               # multiply the values pair wise
[1 4 9 16]

perldl> p transpose $x      # from horizontal vector make a vertical vector

[
 [1]
 [2]
 [3]
 [4]
]

perldl> p $x * transpose($x)    # then multiply the two vectors

[
 [ 1  2  3  4]
 [ 2  4  6  8]
 [ 3  6  9 12]
 [ 4  8 12 16]
]


Gabor


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