Simple...?

Matrix by vector multiplication using MAT:

Say, for example, M() is a matrix of 3 rows by 3 columns, V() is a column vector of 3 rows...

DIM M(1 TO 3,1 TO 3) AS EXT, V(1 TO 3) AS EXT

If, after populating these arrays with data, I wish to replace the data in V() with the result of multiplying M() by V(), as in...

MAT V() = M() * V()

I get an incorrect result, whereas...

MAT V2() = M() * V()

provides the correct result, but I then have to copy V2() into V().

Providing a second dimension in V(), as in V(1 to 3,1 to 1), doesn't help.

What am I missing here? I'm perfectly prepared for someone to tell me that I'm being very stupid!

Michael Bell (using PB/CC5)

Matrix by vector multiplication using MAT:

Say, for example, M() is a matrix of 3 rows by 3 columns, V() is a column vector of 3 rows...

DIM M(1 TO 3,1 TO 3) AS EXT, V(1 TO 3) AS EXT

If, after populating these arrays with data, I wish to replace the data in V() with the result of multiplying M() by V(), as in...

MAT V() = M() * V()

I get an incorrect result, whereas...

MAT V2() = M() * V()

provides the correct result, but I then have to copy V2() into V().

Providing a second dimension in V(), as in V(1 to 3,1 to 1), doesn't help.

What am I missing here? I'm perfectly prepared for someone to tell me that I'm being very stupid!

Michael Bell (using PB/CC5)

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