spectogrd output full of nan with gridtype='gaussian' and relatively large ntrunc

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What steps will reproduce the problem?
1.
# for example with the file spharmonic.py
# double nlons, nlats and ntrunc,
# and add option gridtype='gaussian':

nlons = 2*720; nlats = nlons/2+1
ntrunc = nlats-1
x = Spharmt(nlons,nlats,legfunc='computed', gridtype='gaussian')

2. spharmonic = x.spectogrd(coeffs)

What is the expected output? What do you see instead?
spharmonic should contain a spherical harmonic in real space,
instead, it contains only nan.

What version of the product are you using? On what operating system?
pyspharm-1.0.6, ubuntu 11.10

Remark: this problem does not appear with the function grdtospec()

Original issue reported on code.google.com by [email protected] on 10 Jan 2012 at 5:33