multiply a vector by a matrix line by line
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multiply a vector by a matrix line by line
I am trying to multiply the vector x by the matrix y line by line:
x
100 200 150 25 35
y
1 1 0 0 0
0 0 1 0 1
0 0 0 1 0
to get:
100 200 0 0 0
0 0 150 0 35
0 0 0 25 0
with x and y having any number of columns and y having any number of rows
I tried many thigs but cannot get how to do this...
Please help,
x
100 200 150 25 35
y
1 1 0 0 0
0 0 1 0 1
0 0 0 1 0
to get:
100 200 0 0 0
0 0 150 0 35
0 0 0 25 0
with x and y having any number of columns and y having any number of rows
I tried many thigs but cannot get how to do this...
Please help,
 BenoitM
 Posts: 10
 Joined: Tue Jan 12, 2021 3:04 pm
Re: multiply a vector by a matrix line by line
Your target result implies that you actually want the length of the vector and width of the matrix to conform which seems to be contradicted by the final sentence. However
corrected immediately PL
x ×⍤1⊢ ywill give the answer.
corrected immediately PL

Phil Last  Posts: 628
 Joined: Thu Jun 18, 2009 6:29 pm
 Location: Wessex
Re: multiply a vector by a matrix line by line
The rank operator applies its left function operand to cells of its arguments defined by the ranks in its right vector operand. so in this case 1cells (rows) in each argument are paired. As there is only one 1cell in x it is repeated for each in y

Phil Last  Posts: 628
 Joined: Thu Jun 18, 2009 6:29 pm
 Location: Wessex
Re: multiply a vector by a matrix line by line
..or just using another way:
VeliMatti
x×[2]y
VeliMatti
 VeliMatti
 Posts: 94
 Joined: Sat Nov 28, 2009 3:12 pm
Re: multiply a vector by a matrix line by line
Thank you both!
 BenoitM
 Posts: 10
 Joined: Tue Jan 12, 2021 3:04 pm
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