t_rot takes a single argument, so you need to use (but see update below): 
$e = t_rot([45,45,45]);

[download]
The other thing is that $e will be a transform object which requires you to use it like this: 
$d = $e->apply($c);

[download]
The final thing is that matrix multiplication is the x operator whereas * is component-wise multiplication.

Update: There's a bug in the code/documentation for t_rot. The work-around is to use t_linear and also specify a dims argument: 

$e = t_linear({ rot => [45,45,45], dims => 3});

[download]
The problem can be demonstrated by setting $PDL::Transform::debug = 1;: 
$PDL::Transform::debug = 1;

$e = t_linear({ rot => [45,45,45] });
# the above will emit:
#   PDL::Transform::Linear: assuming 2-D transform (set dims option to
+ change)

[download]

In reply to Re: Using PDL for rotations by pc88mxer
in thread Using PDL for rotations by Anonymous Monk

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