Ummm, since x is the name of the LEFT argument of a verb, I suspect
that you had a global value of x that caused the length error... Try
instead something like (getting rid of some redundant ()s:
cnot_gate =: 3 : '(4 4 $ 1 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0) +/ . * y'
At 23:25 -0400 2007/04/08, Pascal Heus wrote:
Hi:
I'm mostly new to J.
Why do I get a "length error" when I define a verb as shown below (the
dot product of a 4x4 matrix with a 4x1 column vector)
cnot_gate =: 3 : '(4 4 $ 1 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0) (+/ . *) (x)'
and then executes
cnot_gate (,. 0 1 0 1)
|length error: cnot_gate
| (4 4$1 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0) (+/ .*)(x)
The direct call works correctly
(4 4 $ 1 0 0 0 0 1 0 0 0 0 0 1 0 0 1 0) (+/ . *) (,. 0 1 0 1)
0
1
1
0
thanks
Pascal
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