how to write equation in matlab

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Elysi Cochin 2013-1-24

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采纳的回答： Walter Roberson

please can some help me write the equations below in matlab.... in the following link....

http://img545.imageshack.us/img545/8454/equations.png

please do reply.....

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Walter Roberson 2013-1-24

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If I read the equation correctly, then Imu and Isigma do not depend on the x and y parameters and are instead the same for all rows and columns.

Imu = mean2(f)
Isigma = std(f(:), 1);   %the biased standard deviation

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Walter Roberson 2013-1-24

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Read the right hand side of the equations. There is a double summation given that varies x in the outer summation, and varies y in the inner summation. Those variation of "x" and "y" by the summation operators override whatever x and y are given as parameters. As the x and y that are the parameters never appear outside of the summations, the result of the calculation depends only on the grayscale values over the sub-array f(1:R, 1:C) where R and C are constants. So Imu is constant for the image rather than being dependent on the x and y parameters.

The same logic applies for Isigma: it too is dependent only on the image contents and independent of the x and y coordinate given as parameters.

The calculations for Imu and Isigma then become as shown above -- mean2() and the biased standard deviation.

But if you insist, you could instead say,

Imu = ones(size(f)) * mean2(f);
Isigma = ones(size(f)) * std(f(:), 1);  %biased standard deviation

Somewhat pointless as you simply replicate the single value to the size of the array, but if it works for you then go ahead and use it.

Walter Roberson 2013-2-6

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Isigma = var(double(f(:)), 1);

Elysi Cochin 2013-2-6

thank u sir...

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