// Get a RA and Decl from x and y void reverse(double ra0,double de0,float x,float y,double *ra,double *de) { int i; char pcode[4]="TAN"; double phi,theta; struct celprm cel; struct prjprm prj; double rx,ry; rx=x/3600.; ry=y/3600.; // Initialize Projection Parameters prj.flag=0; prj.r0=0.; for (i=0;i<10;prj.p[i++]=0.); // Initialize Reference Angles cel.ref[0]=ra0; cel.ref[1]=de0; cel.ref[2]=999.; cel.ref[3]=999.; cel.flag=0.; if (celset(pcode,&cel,&prj)) { printf("Error in Projection (celset)\n"); return; } else { if (celrev(pcode,rx,ry,&prj,&phi,&theta,&cel,ra,de)) { printf("Error in Projection (celrev)\n"); return; } } return; }
// Get a x and y from a RA and Decl void forward(double ra0,double de0,double ra,double de,float *x,float *y) { int i; char pcode[4]="TAN"; double phi,theta; struct celprm cel; struct prjprm prj; double rx,ry; // Initialize Projection Parameters prj.flag=0; prj.r0=0.; for (i=0;i<10;prj.p[i++]=0.); // Initialize Reference Angles cel.ref[0]=ra0; cel.ref[1]=de0; cel.ref[2]=999.; cel.ref[3]=999.; cel.flag=0.; if (celset(pcode,&cel,&prj)) { printf("Error in Projection (celset)\n"); return; } else { if (celfwd(pcode,ra,de,&cel,&phi,&theta,&prj,&rx,&ry)) { printf("Error in Projection (celfwd)\n"); return; } } *x=rx*3600.; *y=ry*3600.; return; }
int main() { char text[80]; int ci, crval1, crval2, ilat, ilng, j, k, latpole, lonpole, stat[361], status; float xr[512], yr[512]; double lat[181], lng[361], phi[361], theta[361], x[361], y[361]; struct celprm native, celestial; printf( "Testing WCSLIB celestial coordinate transformation routines (tcel1.c)\n" "---------------------------------------------------------------------\n"); /* List status return messages. */ printf("\nList of cel status return values:\n"); for (status = 1; status <= 6; status++) { printf("%4d: %s.\n", status, cel_errmsg[status]); } printf("\n"); /* Initialize. */ celini(&native); /* Reference angles for the native graticule (in fact, the defaults). */ native.ref[0] = 0.0; native.ref[1] = 0.0; /* Set up Bonne's projection with conformal latitude at +35. */ strcpy(native.prj.code, "BON"); native.prj.pv[1] = 35.0; /* Celestial graticule. */ celini(&celestial); celestial.prj = native.prj; /* PGPLOT initialization. */ strcpy(text, "/xwindow"); cpgbeg(0, text, 1, 1); /* Define pen colours. */ cpgscr(0, 0.0f, 0.0f, 0.0f); cpgscr(1, 1.0f, 1.0f, 0.0f); cpgscr(2, 1.0f, 1.0f, 1.0f); cpgscr(3, 0.5f, 0.5f, 0.8f); cpgscr(4, 0.8f, 0.5f, 0.5f); cpgscr(5, 0.8f, 0.8f, 0.8f); cpgscr(6, 0.5f, 0.5f, 0.8f); cpgscr(7, 0.8f, 0.5f, 0.5f); cpgscr(8, 0.3f, 0.5f, 0.3f); /* Define PGPLOT viewport. */ cpgenv(-180.0f, 180.0f, -90.0f, 140.0f, 1, -2); /* Loop over CRVAL2, LONPOLE, and LATPOLE with CRVAL1 incrementing by */ /* 15 degrees each time (it has an uninteresting effect). */ crval1 = -180; for (crval2 = -90; crval2 <= 90; crval2 += 30) { for (lonpole = -180; lonpole <= 180; lonpole += 30) { for (latpole = -1; latpole <= 1; latpole += 2) { /* For the celestial graticule, set the celestial coordinates of * the reference point of the projection (which for Bonne's * projection is at the intersection of the native equator and * prime meridian), the native longitude of the celestial pole, * and extra information needed to determine the celestial * latitude of the native pole. These correspond to FITS keywords * CRVAL1, CRVAL2, LONPOLE, and LATPOLE. */ celestial.ref[0] = (double)crval1; celestial.ref[1] = (double)crval2; celestial.ref[2] = (double)lonpole; celestial.ref[3] = (double)latpole; /* Skip invalid values of LONPOLE. */ if (celset(&celestial)) { continue; } /* Skip redundant values of LATPOLE. */ if (latpole == 1 && fabs(celestial.ref[3]) < 0.1) { continue; } /* Buffer PGPLOT output. */ cpgbbuf(); cpgeras(); /* Write a descriptive title. */ sprintf(text, "Bonne's projection (BON) - 15 degree graticule"); printf("\n%s\n", text); cpgtext(-180.0f, -100.0f, text); sprintf(text, "centred on celestial coordinates (%7.2f,%6.2f)", celestial.ref[0], celestial.ref[1]); printf("%s\n", text); cpgtext (-180.0f, -110.0f, text); sprintf(text, "with north celestial pole at native coordinates " "(%7.2f,%7.2f)", celestial.ref[2], celestial.ref[3]); printf("%s\n", text); cpgtext(-180.0f, -120.0f, text); /* Draw the native graticule faintly in the background. */ cpgsci(8); /* Draw native meridians of longitude. */ for (j = 0, ilat = -90; ilat <= 90; ilat++, j++) { lat[j] = (double)ilat; } for (ilng = -180; ilng <= 180; ilng += 15) { lng[0] = (double)ilng; if (ilng == -180) lng[0] = -179.99; if (ilng == 180) lng[0] = 179.99; /* Dash the longitude of the celestial pole. */ if ((ilng-lonpole)%360 == 0) { cpgsls(2); cpgslw(5); } cels2x(&native, 1, 181, 1, 1, lng, lat, phi, theta, x, y, stat); k = 0; for (j = 0; j < 181; j++) { if (stat[j]) { if (k > 1) cpgline(k, xr, yr); k = 0; continue; } xr[k] = -x[j]; yr[k] = y[j]; k++; } cpgline(k, xr, yr); cpgsls(1); cpgslw(1); } /* Draw native parallels of latitude. */ lng[0] = -179.99; lng[360] = 179.99; for (j = 1, ilng = -179; ilng < 180; ilng++, j++) { lng[j] = (double)ilng; } for (ilat = -90; ilat <= 90; ilat += 15) { lat[0] = (double)ilat; cels2x(&native, 361, 1, 1, 1, lng, lat, phi, theta, x, y, stat); k = 0; for (j = 0; j < 361; j++) { if (stat[j]) { if (k > 1) cpgline(k, xr, yr); k = 0; continue; } xr[k] = -x[j]; yr[k] = y[j]; k++; } cpgline(k, xr, yr); } /* Draw a colour-coded celestial coordinate graticule. */ ci = 1; /* Draw celestial meridians of longitude. */ for (j = 0, ilat = -90; ilat <= 90; ilat++, j++) { lat[j] = (double)ilat; } for (ilng = -180; ilng <= 180; ilng += 15) { lng[0] = (double)ilng; if (++ci > 7) ci = 2; cpgsci(ilng?ci:1); /* Dash the reference longitude. */ if ((ilng-crval1)%360 == 0) { cpgsls(2); cpgslw(5); } cels2x(&celestial, 1, 181, 1, 1, lng, lat, phi, theta, x, y, stat); k = 0; for (j = 0; j < 181; j++) { if (stat[j]) { if (k > 1) cpgline(k, xr, yr); k = 0; continue; } /* Test for discontinuities. */ if (j > 0) { if (fabs(x[j]-x[j-1]) > 4.0 || fabs(y[j]-y[j-1]) > 4.0) { if (k > 1) cpgline(k, xr, yr); k = 0; } } xr[k] = -x[j]; yr[k] = y[j]; k++; } cpgline(k, xr, yr); cpgsls(1); cpgslw(1); } /* Draw celestial parallels of latitude. */ for (j = 0, ilng = -180; ilng <= 180; ilng++, j++) { lng[j] = (double)ilng; } ci = 1; for (ilat = -90; ilat <= 90; ilat += 15) { lat[0] = (double)ilat; if (++ci > 7) ci = 2; cpgsci(ilat?ci:1); /* Dash the reference latitude. */ if (ilat == crval2) { cpgsls(2); cpgslw(5); } cels2x(&celestial, 361, 1, 1, 1, lng, lat, phi, theta, x, y, stat); k = 0; for (j = 0; j < 361; j++) { if (stat[j]) { if (k > 1) cpgline(k, xr, yr); k = 0; continue; } /* Test for discontinuities. */ if (j > 0) { if (fabs(x[j]-x[j-1]) > 4.0 || fabs(y[j]-y[j-1]) > 4.0) { if (k > 1) cpgline(k, xr, yr); k = 0; } } xr[k] = -x[j]; yr[k] = y[j]; k++; } cpgline(k, xr, yr); cpgsls(1); cpgslw(1); } /* Flush PGPLOT buffer. */ cpgebuf(); printf(" Type <RETURN> for next page: "); getc(stdin); /* Cycle through celestial longitudes. */ if ((crval1 += 15) > 180) crval1 = -180; /* Skip boring celestial latitudes. */ if (crval2 == 0) break; } if (crval2 == 0) break; } } cpgask(0); cpgend(); return 0; }
int celset_(int *cel) { return celset((struct celprm *)cel); }