svn-gvsig-desktop / trunk / libraries / libjni-proj4 / src / nad_intr.c @ 7098
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/* Determine nad table correction value */
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#ifndef lint
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static const char SCCSID[]="@(#)nad_intr.c 4.2 95/09/23 GIE REL"; |
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#endif
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#define PJ_LIB__
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#include <projects.h> |
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LP |
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nad_intr(LP t, struct CTABLE *ct) {
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LP val, frct; |
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ILP indx; |
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double m00, m10, m01, m11;
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FLP *f00, *f10, *f01, *f11; |
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long index;
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int in;
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indx.lam = floor(t.lam /= ct->del.lam); |
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indx.phi = floor(t.phi /= ct->del.phi); |
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frct.lam = t.lam - indx.lam; |
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frct.phi = t.phi - indx.phi; |
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val.lam = val.phi = HUGE_VAL; |
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if (indx.lam < 0) { |
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if (indx.lam == -1 && frct.lam > 0.99999999999) { |
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++indx.lam; |
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frct.lam = 0.;
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} else
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return val;
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} else if ((in = indx.lam + 1) >= ct->lim.lam) { |
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if (in == ct->lim.lam && frct.lam < 1e-11) { |
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--indx.lam; |
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frct.lam = 1.;
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} else
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return val;
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} |
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if (indx.phi < 0) { |
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if (indx.phi == -1 && frct.phi > 0.99999999999) { |
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++indx.phi; |
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frct.phi = 0.;
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} else
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return val;
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} else if ((in = indx.phi + 1) >= ct->lim.phi) { |
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if (in == ct->lim.phi && frct.phi < 1e-11) { |
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--indx.phi; |
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frct.phi = 1.;
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} else
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return val;
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} |
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index = indx.phi * ct->lim.lam + indx.lam; |
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f00 = ct->cvs + index++; |
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f10 = ct->cvs + index; |
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index += ct->lim.lam; |
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f11 = ct->cvs + index--; |
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f01 = ct->cvs + index; |
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m11 = m10 = frct.lam; |
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m00 = m01 = 1. - frct.lam;
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m11 *= frct.phi; |
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m01 *= frct.phi; |
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frct.phi = 1. - frct.phi;
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m00 *= frct.phi; |
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m10 *= frct.phi; |
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val.lam = m00 * f00->lam + m10 * f10->lam + |
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m01 * f01->lam + m11 * f11->lam; |
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val.phi = m00 * f00->phi + m10 * f10->phi + |
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m01 * f01->phi + m11 * f11->phi; |
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return val;
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} |