In PDL, '*' is for scalar multiplication, which automatically "broadcasts" up so that two ndarrays can be scalar-multiplied so the result is each of the six "slots" being the product of the two numbers. Matrix multiplication is the overload of the 'x' operator. 
pdl> p $x = sequence(2,2)
[
 [0 1]
 [2 3]
]

pdl> p $y = sequence(2,2) + 3
[
 [3 4]
 [5 6]
]

pdl> p $x * $y
[
 [ 0  4]
 [10 18]
]

pdl> p $x x $y
[
 [ 5  6]
 [21 26]
]

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In reply to Re^2: Fast matrix multiplication by etj
in thread Fast matrix multiplication by ludo

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