Amplitude adjustment on integral

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PetterS 2015-3-4

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回答： Andrew Newell 2015-3-4

Hi. I have a lot of electromagnetic spectrums that show the correct distribution (shape of the curve) of wavelengths, but I need to adjust the integrated value so that it matches another measured value that I have.

So in other words, I need to adjust the amplitude (up and down) of the curve where the values are in (W/m²)/nm so that the integral becomes another value that is in W/m² without changing the distribution/shape.

How can this be done? And is there any specific integration method that is extra good and should be used to integrate data that looks like this (quickly jumps up and down etc.)?

Thanks.

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Roger Stafford 2015-3-4

It's simple algebra. Multiply the amplitude by a constant equal to the ratio of the desired integral value divided by the integral value you obtained.

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Answer 1

Andrew Newell 2015-3-4

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Just calculate the integral (see integral), say

q = integral(fun,xmin,xmax);

and then multiply your function by your_value / q. The help page has an example, "Improper Integral of Oscillatory Function", with adjustments that would work just as well for a proper integral.