96 lines
3.7 KiB
C++
96 lines
3.7 KiB
C++
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/********************************************************
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* ██████╗ ██████╗████████╗██╗
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* ██╔════╝ ██╔════╝╚══██╔══╝██║
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* ██║ ███╗██║ ██║ ██║
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* ██║ ██║██║ ██║ ██║
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* ╚██████╔╝╚██████╗ ██║ ███████╗
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* ╚═════╝ ╚═════╝ ╚═╝ ╚══════╝
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* Geophysical Computational Tools & Library (GCTL)
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*
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* Copyright (c) 2022 Yi Zhang (yizhang-geo@zju.edu.cn)
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*
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* GCTL is distributed under a dual licensing scheme. You can redistribute
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* it and/or modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, either version 2
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* of the License, or (at your option) any later version. You should have
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* received a copy of the GNU Lesser General Public License along with this
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* program. If not, see <http://www.gnu.org/licenses/>.
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*
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* If the terms and conditions of the LGPL v.2. would prevent you from using
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* the GCTL, please consider the option to obtain a commercial license for a
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* fee. These licenses are offered by the GCTL's original author. As a rule,
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* licenses are provided "as-is", unlimited in time for a one time fee. Please
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* send corresponding requests to: yizhang-geo@zju.edu.cn. Please do not forget
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* to include some description of your company and the realm of its activities.
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* Also add information on how to contact you by electronic and paper mail.
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******************************************************/
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#include "gctl/maths/legendre.h"
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#include "magnetometric.h"
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double gctl::mmr_hemisphere_bz(double x, double y, double cx, double cy, double I,
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double hx, double hy, double hr, double cndt, double bkg_cndt, size_t order)
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{
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if (hr <= 0)
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{
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throw gctl::runtime_error("Invalid depression radius. From gctl::mmr_hemisphere_bz(...)");
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}
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double d = sqrt((cx - hx)*(cx - hx) + (cy - hy)*(cy - hy));
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double r = sqrt((x - hx)*(x - hx) + (y - hy)*(y - hy));
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double l = sqrt((cx - x)*(cx - x) + (cy - y)*(cy - y));
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double ct = (d*d + r*r - l*l)/(2.0*d*r);
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double rho = 1.0/cndt;
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double bkg_rho = 1.0/bkg_cndt;
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//double st = sqrt(1.0 - ct*ct);
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//if ((x - hx)*(cy - hy) - (cx - hx)*(y - hy) < 0) st *= -1.0;
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double st = ((x - hx)*(cy - hy) - (cx - hx)*(y - hy))/(r*d);
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double Cn, Bz = 0.0;
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if (r <= GCTL_ZERO)
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{
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return 0.0;
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}
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else if (d > hr)
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{
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if (r <= hr)
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{
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for (size_t i = 1; i <= order; i++)
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{
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Cn = (rho - bkg_rho)/((i+1)*rho + i*bkg_rho);
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Bz += Cn*pow(r/d, i+1)*gctl::legendre_polynomials(i, ct, true);
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}
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}
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else
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{
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for (size_t i = 1; i <= order; i++)
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{
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Cn = (rho - bkg_rho)/((i+1)*rho + i*bkg_rho);
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Bz += Cn*pow(hr/r, i)*pow(hr/d, i+1)*gctl::legendre_polynomials(i, ct, true);
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}
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}
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}
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else
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{
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if (r <= hr)
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{
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for (size_t i = 1; i <= order; i++)
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{
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Cn = (rho - bkg_rho)/((i+1)*rho + i*bkg_rho);
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Bz += Cn*pow(r/hr, i+1)*pow(d/hr, i)*gctl::legendre_polynomials(i, ct, true);
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}
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}
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else
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{
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for (size_t i = 1; i <= order; i++)
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{
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Cn = (rho - bkg_rho)/((i+1)*rho + i*bkg_rho);
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Bz += Cn*pow(d/r, i)*gctl::legendre_polynomials(i, ct, true);
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}
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}
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}
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Bz *= GCTL_MU0*I*st/(4.0*GCTL_Pi*r); // 转换为z轴朝上的坐标体系 -1 * -1
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return Bz;
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}
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