# Scale and shape parameters of Gamma mixture distributions

I used the function mix (package mixdist) to fit Gamma mixture distributions. The function gives mu and sigma parameters (output below). How can I find the scale and shape parameters ?

Parameters:
pi    mu sigma
1 0.2089 185.7 285.4
2 0.7911 530.1 423.5


Hint: Page 4 of the manual of the package indicates that mu represents the mean and sigma represents the standard deviation (square root of the variance):

https://cran.r-project.org/web/packages/mixdist/mixdist.pdf

Since the Gamma distribution has closed form mean and standard deviation, you can easily transformed into scale and shape:

https://en.wikipedia.org/wiki/Gamma_distribution

• From the link about Gamma distribution, mean = scale x shape. How can I find the scale and shape values from only the mean value ? – Marine Aug 26 '16 at 13:33