Calculating IGRF field from spherical expansion

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gammaray
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Calculating IGRF field from spherical expansion

Post by gammaray »

Have you been able to calculate proper magnetic field values from IGRF magnetic potential spherical expansion formula? Coefficients for upto degree N=13 are available at IAGAs webpage but when I calculated potential and took derivative of it to get magnetic field, it was quite off by magnitude, like over 10000 nT at least which too much to be right. But I don't see any obvious mistake in my short code either.

I would guess that Matlab's legendre(N,cos((90-latutude)*pi/180), 'norm') gives right kind of Legendre polynomials.

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