What is the formula for calculating the FWHM of a gaussian function?

[peterjaybee]

Hi,

I have a gaussian of the form
$$exp[-\frac{\pi*x^{2}}{A^2}]$$.

I know that the FWHM=0.939A, but I cannot prove it.

I Let $$exp[-\frac{\pi*x^{2}}{A^2}=0.5$$ (i.e. the half maximum part)

taking natural logs I get rid of the exponential, but then which bit represents the full width?

 

[mathman]

Write x = kA and compute k=(-ln(.5)/π)^1/2

Your Gaussian looks funny.