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From: Ben <bw.games_n0spam@gmail.nospam.com>
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Subject: Re: Interpolation of matrix
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Date: Fri, 09 Nov 2007 10:45:38 GMT
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PB wrote:
> Den Thu, 08 Nov 2007 14:30:22 +0000 skrev Ben:
> 
>> Hi there,
>>
>> I'm trying to perform some operations on a matrix - I have a 20x20
>> matrix that I've got to remove some rows from the top, and re-generate
>> lines at the bottom to leave the matrix the same size as it was.
>>
>> So, say I have a 10x10 matrix, I remove the top row. What I now want to
>> do is generate a row between the row at the bottom, and the one above
>> it, that I can put in to keep it 10x10.
>>
>> I've looked at interp2, and it sort of seems to do what I want, e.g
>> running interp2(Matrix) gives me a 19x19 matrix with an interpolated row
>> between each. Is there any way to point interp2 at a matrix, with row
>> vector 9, and get it to return a 1x10 matrix containing the interpolated
>> row between row vectors 9 and 10, that I can just add to the first
>> matrix?
>>
>> I believe interp2 can sort-of do this, using Xi and Yi, but that appears
>> to be more related to generating an interpolated value from two data
>> points, not two rows?
>>
>> Anyone have any advice?
>>
>> Thanks,
>>
>> Ben
> 
> Does this help?
> 
> a=magic(3);
> a(:,3)=[]   % remove last row
> ix=1:0.5:2;
> [xi,yi]=meshgrid(ix)
> y=interp2(a,xi,yi)
> 
> 
> /PB

Thanks, but your a= line actually removes the last column and not the 
last row...

I changed it to remove the last column, but the final result bears no 
resemblance to the original square I'm not sure how the meshgrid of ix 
interacts with the interpolation, which is what I think is causing the 
wrong results as I changed it from column to row...?