EVOLUTION-MANAGER

Edit File: PJ_boggs.c

#define PJ_LIB__ #include <math.h> #include "projects.h" PROJ_HEAD(boggs, "Boggs Eumorphic") "\n\tPCyl., no inv., Sph."; # define NITER 20 # define EPS 1e-7 # define FXC 2.00276 # define FXC2 1.11072 # define FYC 0.49931 static XY s_forward (LP lp, PJ *P) { /* Spheroidal, forward */ XY xy = {0.0,0.0}; double theta, th1, c; int i; (void) P; theta = lp.phi; if (fabs(fabs(lp.phi) - M_HALFPI) < EPS) xy.x = 0.; else { c = sin(theta) * M_PI; for (i = NITER; i; --i) { theta -= th1 = (theta + sin(theta) - c) / (1. + cos(theta)); if (fabs(th1) < EPS) break; } theta *= 0.5; xy.x = FXC * lp.lam / (1. / cos(lp.phi) + FXC2 / cos(theta)); } xy.y = FYC * (lp.phi + M_SQRT2 * sin(theta)); return (xy); } PJ *PROJECTION(boggs) { P->es = 0.; P->fwd = s_forward; return P; }