How to reverse the normalization function normc/normr?
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I have used the function of "normr/normr" to normalize a matrix, but how can I reverse the normalization? Thank you very much!
2 个评论
Image Analyst
2015-9-16
What happened to the original matrix? Why did you lose it?
I don't have the normr() function. Please list which toolbox it's in in the Products section below.
kokin
2015-9-16
采纳的回答
If you haven't discarded the original data, there is nothing to restore. The "restored" matrix is the original one that you already have. If you plan to throw that data away, the best thing would be to save the row-wise (or column-wise) norms and use them when needed to undo normalization, e.g.,
A =
1 5 9 13
2 6 10 14
3 7 11 15
4 8 12 16
>> nr=sqrt(sum(A.^2,2)); %row-wise norms
>> B=bsxfun(@rdivide,A,nr) %same as B=normr(A)
B =
0.0602 0.3010 0.5417 0.7825
0.1091 0.3273 0.5455 0.7638
0.1493 0.3483 0.5473 0.7463
0.1826 0.3651 0.5477 0.7303
>> Arev=bsxfun(@times,B,nr) %reverse
Arev =
1.0000 5.0000 9.0000 13.0000
2.0000 6.0000 10.0000 14.0000
3.0000 7.0000 11.0000 15.0000
4.0000 8.0000 12.0000 16.0000
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