# Re: multiplication of matrices

• From: Frederic Parrenin <parrenin gmail com>
• To: Andreas Guelzow <aguelzow pyrshep ca>
• Cc: gnumeric-list gnome org
• Subject: Re: multiplication of matrices
• Date: Wed, 17 Aug 2011 21:54:50 +0200

Actually my title is confusing.
I would like to do a cell by cell multiplication of matrices (simple '*' operator).

So to simplify, is there a multiplication operator which gives blank when one of the two operand is blank?

Best,

Frédéric

2011/8/17 Andreas Guelzow
On Wed, 2011-08-17 at 18:29 +0200, Frederic Parrenin wrote:

> I would like to multiply two matrices in Gnumeric.
> The first one has cells without any content.
> The second one has all its cells with content.
>
>
> When I do the multiplication, the cells without content are used as if
> '0' was placed in these cells.
> That is, the multiplication of a cell without content with a cell with
> content is '0'.
> But in this case I would like the resulting cell to not have any
> content.
>
>
> Do you know of a way to circumwent this problem?

Assuming the blank is in the first row of the first matrix, matrix
multiplication will use this entry to calculate each entry in the first
row of the result, so you want all of those entries to be blank?

In other words if you have to 10 by 10 matrices and one entry of each
row of the first matrix is blank do you really want the resulting matrix
to be completely blank?

If that is the case you cannot use the MMULT function but need to define

Andreas
>

--
Andreas Guelzow <aguelzow pyrshep ca>

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