Row vector (multiplication by a column vector)
02-01-2023, 02:21 PM
Post: #1
 DrD Senior Member Posts: 1,133 Joined: Feb 2014
Row vector (multiplication by a column vector)
Example: 3x1 column vector multiplying a 1x3 row vector

a:=[[1,2,3]];
b:=[4,5,6];

a*b => "dotvecteur Error: Invalid dimension"

However, by converting b to a 1x3 matrix first, works.
b:=TRN(TRN(b)); // Converts the 1x3 vector to a 1x3 matrix ...

a*b => [[4,5,6],[8,10,12],[12,15,18]]

Requiring conversion from a row vector to a 1x3 matrix data type is an extra step that could benefit from software improvement, in cases such as these.
02-01-2023, 09:56 PM
Post: #2
 jte Member Posts: 217 Joined: Feb 2014
RE: Row vector (multiplication by a column vector)
When I took my first linear algebra course, I was taught that vectors are simply special cases of matrices (1×n or n×1, rather than m×n).
02-02-2023, 11:16 AM
Post: #3
 parisse Senior Member Posts: 1,270 Joined: Dec 2013
RE: Row vector (multiplication by a column vector)
On the other hand, if you handle this case without error, it will be harder to detect a real error...
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