Evaluate an S2FunHarmonic on an equispaced grid in spherical coordinates \[(\theta_a,\rho_b) = (\frac{\pi a}{Htheta-1},\frac{2\pi b}{Hrho})\] where \(a=0,...,Htheta-1\) and \(b=0,...,Hrho-1\).
Therefore we transform the Harmonic series to an ordinary Fourier series equivalent as in the function eval. Afterwards, we use an equispaced FFT instead of the NFFT.
Syntax
f = evalEquispacedFFT(sF,v)Input
| sF | S2FunHarmonic |
| v | quadratureS2Grid - 'ClenshawCurtis' |
Output
| f | values at this grid points |
Example
construct quadrature grid and evaluate there. Output will be a unique part of this grid
sF = S2FunHarmonic.smiley;
v = quadratureS2Grid(100,'ClenshawCurtis');
f = evalEquispacedFFT(sF,v);for big grid sizes the construction of the quadrature grid is memory expansive. Hence construct a struct, but the output is full sized
v = struct('scheme','ClenshawCurtis','bandwidth',1500)
f = evalEquispacedFFT(sF,v);v =
struct with fields:
scheme: 'ClenshawCurtis'
bandwidth: 1500