Find value of variable in a equality

Hi, i have to estimate the sigma from here,
(dB) = (1/sqrt(2*pi*sigma))*exp(-(BW-m)²/2(sigma)²)
as you see is the gaussian densitiy function.
I know the value of (dB), and the (BW-m)² polynomial, so my question is,
How can I get the sigma value?
Thank you all, my first time here, it's an honor.

 Accepted Answer

José-Luis
José-Luis on 12 Nov 2012
Edited: José-Luis on 12 Nov 2012
This is not really a Matlab question. You could explicitely solve this equation using some arithmetic. That said, you could always use the symbolic toolbox to do that for you:
syms x dB val
solve(1/sqrt(2*pi*x)*exp(-(val/(2*x)))-dB)
ans =
-val/lambertw(0, -2*pi*dB^2*val)
You just need to replace val (BW-m)^2 and dB in that expression.

1 Comment

That's what I needed, thank you so much José-Luis.

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on 12 Nov 2012

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