Quickstart

Load the package

using SHTns

Define your SHTnsCfg configuration for some maximum spherical harmonic degree lmax

lmax = 64
cfg = SHTnsCfg(lmax)

SHTnsCfg{Real, SHTns.Orthonormal, SHTns.QuickInit}
lmax: 64, mmax: 64, mres: 1, nlat: 66, nphi: 140

Create some spatial data d, using the latitude and longitude from SHTns.grid

function spat_func_test(theta, phi)
	return 1.0 + 0.01*cos(theta)  + 0.1*(3cos(theta)*cos(theta) - 1.0) +	#// Y00, Y10, Y20
	(cos(phi) + 0.3*sin(phi)) * sin(theta)	+ #// Y11
	(cos(2phi) + 0.1*sin(2phi)) * sin(theta)*sin(theta) * (7.0* cos(theta)*cos(theta) - 1.0) * 3/8 	#// Y42
end

θ,ϕ = SHTns.grid(cfg)
d = spat_func_test.(θ, ϕ')

Transform the data d to the spectral coefficients q (i.e. perform an analysis)

q = SHTns.analys(cfg, d)

Transform back to spatial data (i.e. perform a synthesis)

d2 = SHTns.synth(cfg, q)
d2 ≈ d

true

These transforms can also be performed in place

q2 = similar(q)
SHTns.analys!(cfg, d2, q2)
q2 ≈ q

true

SHTns.synth!(cfg, q2, d2)
d2 ≈ d

true