# Matlab Zeros, What type of matrix will I get from this?

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Jose Cuevas on 26 Feb 2021
Commented: Jose Cuevas on 1 Mar 2021
Hello, I am trying to understand a code that I using in my project, could someone tell me what do I get from this operation?
scan_trous_carres0=zeros((size_lambda*size_period*size_etching_depth*size_phi),9)
The 9 comes from a column of a text file that where I am getting data, I am trying to figure out why I am I multiplying the values inside the parenthesis and then I have the 9 outisde that parenthesis. What kind of matrix will I get?
##### 2 CommentsShowHide 1 older comment
dpb on 26 Feb 2021
Or, just set a breakpoint in the debugger and poke around when you get there...

Adam Danz on 26 Feb 2021
Edited: Adam Danz on 26 Feb 2021
> could someone tell me what do I get from this operation
Assuming your variables are scalar (1 value) or, when multipled, produce a scalar, scan_trous_carres0 will be an mx9 matrix of 0s where m is the result of the multiplication. Try it, as dpb suggested, or read about it in the documentation.
> I am trying to figure out why I am I multiplying the values inside the parenthesis
We certainly don't know why you're doing that ðŸ™‚. Apparently those 4 variables describe lengths or sizes of something and your output matrix needs to have that many rows. Are those values scalar? Vectors that, when combined, produce a scalar? We don't know.
This function is commonly used to preallocate loop-variables.
> and then I have the 9 outisde that parenthesis
Well, apparently you need 9 columns of 0s. size(x,y) produces a matrix of 0s of size x*y.
> What kind of matrix will I get?
A matrix of 0s of class double
To confirm,
class(scan_trous_carres0)
Jose Cuevas on 1 Mar 2021
Thank you, it appears that I was preparing a 2D matrix of 9 columns with a long range of values in x. The values came from a loop in python, it took me a while to connect the dots.

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