libsharp2/libsharp/sharp_legendre_table.h

97 lines
3.6 KiB
C

/*
* This file is part of libsharp.
*
* Redistribution and use in source and binary forms, with or without
* met:
*
* 1. Redistributions of source code must retain the above copyright
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*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
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*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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/*! \file sharp_legendre_table.h
* Interface for computing tables of the normalized associated Legendre transform
*
* Copyright (C) 2017 Dag Sverre Seljebotn
* \author Dag Sverre Seljebotn
*
* Note: This code was mainly copied from libpsht; only a small high-level wrapper added
*/
#ifndef SHARP_LEGENDRE_TABLE_H
#define SHARP_LEGENDRE_TABLE_H
#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
#ifndef NO_LEGENDRE_TABLE
/*! Returns a table of the normalized associated Legendre polynomials. m is a single
fixed argument and a table for multiple l and cos(theta) is provided.
(Internally, sin(theta) is also used for part of the computation, making theta
the most convenient argument.)
NOTE: Support for spin-weighted Legendre functions is on the TODO-list. Only spin=0
is supported now.
\param m The m-value to compute a table for; must be >= 0
\param spin The spin parameter; pass 0 for the regular associated Legendre functions.
NOTE: This is present for future compatability, currently only 0 is supported.
\param lmax A table will be provided for l = m .. lmax
\param ntheta How many theta values to evaluate for
\param theta Contiguous 1D array of theta values
\param theta_stride See below
\param l_stride See below
\param spin_stride See below. "ispin" will always be 0 if spin==0, or 0 for positive spin
and 1 for the corresponding negative spin otherwise.
\param out Contiguous 3D array that will receive the output. Each output entry
is assigned to out[itheta * theta_stride + (l - m) * l_stride + ispin * spin_stride].
*/
void sharp_normalized_associated_legendre_table(
ptrdiff_t m,
int spin,
ptrdiff_t lmax,
ptrdiff_t ntheta,
/* contiguous 1D array of theta values to compute for,
contains ntheta values */
double *theta,
/* contiguous 2D array, in "theta-major ordering". Has `ntheta`
rows and `ncols` columns. Indexed as out[itheta * ncols + (l - m)].
If `ncols > lmax - m` then those entries are not accessed.
*/
ptrdiff_t theta_stride,
ptrdiff_t l_stride,
ptrdiff_t spin_stride,
double *out
);
#endif
#ifdef __cplusplus
}
#endif
#endif