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Jack, The definition of sigma in dfgwfs includes the factor of 2 (or sqrt of 2) that would conventionally be expressed inside the weighting function. sgma = (float)nwl / ( PI * sqrt ( 2.0 ) ); which results in sig2 = sgma**2 = nwl**2 / 2 * PI**2 therefore the factor of 2 is included in sig2 the variable aa: aa = 1. / ( sig2 * PI ); which is expressed in the weighting function (with sig2 rather than 2 * sig2): w[iw-1][jw-1] = aa * exp ( - ( x*x + y*y ) / sig2 ); if the factor of 2 were not included in sgma, it would be accounted for in aa and w as: aa = 1. / ( 2 ** sig2 * PI ); which is expressed in the weighting function: w[iw-1][jw-1] = aa * exp ( - ( x*x + y*y ) / 2 ** sig2 ); so essentially we're only changing the definition of sgma in dfgwfs.f to include the factor of 2 so we don't need to account for it in aa and w. I did a quick napkin run-down of the terms and the math seems correct. Do you agree? Michael James Unidata > Hi, > > I was looking at the code for the Gaussian smoother in GEMPAK called dfgwfs > and came across what might be an error, but I wanted to run it by you to make > sure. The weighting function used is: > > > > Where and N is the number of grid points in a wavelength. I'm wondering if > ? should be given instead by . This value for sigma seems to be correct > given your definition of W. Would someone please take a look? > > > > Thanks, > > Jack > > > > Jack Dostalek > > Cooperative Institute for Research in the Atmosphere > > Colorado State University > > Foothills Campus > > 1375 Campus Delivery > > Fort Collins, CO 80523-1375 > > (970) 491-8326 > > address@hidden > > > > > > > > > Ticket Details =================== Ticket ID: MJB-537359 Department: Support GEMPAK Priority: Normal Status: Open