Cartography-Projection-GCTP

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gctpc/robfor.c  view on Meta::CPAN

double dlon;
double p2;
long ip1;

/* Forward equations
  -----------------*/
dlon = adjust_lon(lon - lon_center);
p2 = fabs(lat / 5.0 / .01745329252);
ip1 = (long) (p2 - EPSLN);

/* Stirling's interpolation formula (using 2nd Diff.)
---------------------------------------------------*/
p2 -= (double) ip1;
*x = R * (xlr[ip1 + 2] + p2 * (xlr[ip1 + 3] - xlr[ip1 + 1]) / 2.0 +
          p2 * p2 * (xlr[ip1 + 3] - 2.0 * xlr[ip1 + 2] + xlr[ip1 + 1])/2.0) * 
          dlon + false_easting;

if (lat >= 0)
   *y = R * (pr[ip1 + 2] + p2 * (pr[ip1 + 3] - pr[ip1 +1]) / 2.0 + p2 * p2 *
            (pr[ip1 + 3] - 2.0 * pr[ip1 + 2] + pr[ip1 + 1]) / 2.0) * PI / 2.0 +
	    false_northing;

gctpc/robinv.c  view on Meta::CPAN

x -= false_easting;
y -= false_northing;

yy = 2.0 * y / PI / R;
phid = yy * 90.0;
p2 = fabs(phid / 5.0);
ip1 = (long) (p2 - EPSLN);
if (ip1 == 0)
   ip1 = 1;

/* Stirling's interpolation formula as used in forward transformation is 
   reversed for first estimation of LAT. from rectangular coordinates. LAT.
   is then adjusted by iteration until use of forward series provides correct 
   value of Y within tolerance.
---------------------------------------------------------------------------*/
for (i = 0;;)
   {
   u = pr[ip1 + 3] - pr[ip1 + 1];
   v = pr[ip1 + 3] - 2.0 * pr[ip1 + 2] + pr[ip1 + 1];
   t = 2.0 * (fabs(yy) - pr[ip1 + 2]) / u;
   c = v / u;

gctpc/robinv.c  view on Meta::CPAN

      if (ip1 < 0)
           {
           p_error("Too many iterations in inverse","robinv-conv");
           return(234);
           }
      }
   }
*lat  = phid * .01745329252;

/* calculate  LONG. using final LAT. with transposed forward Stirling's 
   interpolation formula.
---------------------------------------------------------------------*/
*lon = lon_center + x / R / (xlr[ip1 + 2] + p2 * (xlr[ip1 + 3] - xlr[ip1 + 1])
                      / 2.0 + p2 * p2 * (xlr[ip1 + 3] - 2.0 * xlr[ip1 + 2] + 
                      xlr[ip1 + 1]) / 2.0);
*lon = adjust_lon(*lon);

return(OK);
}

gctpc/wivfor.c  view on Meta::CPAN

PURPOSE:	Transforms input longitude and latitude to Easting and
		Northing for the Wagner IV projection.  The
		longitude and latitude must be in radians.  The Easting
		and Northing values will be returned in meters.

PROGRAMMER              DATE		REASON
----------              ----		------
D. Steinwand, EROS      May, 1991
S. Nelson, EROS		Feb, 1995	Changed perror to p_error.

This function was implemented with formulas supplied by John P. Snyder.

ALGORITHM REFERENCES

1.  Snyder, John P. and Voxland, Philip M., "An Album of Map Projections",
    U.S. Geological Survey Professional Paper 1453 , United State Government
    Printing Office, Washington D.C., 1989.

2.  Snyder, John P., Personal correspondence, January 1991.
*******************************************************************************/
#include "cproj.h"

gctpc/wivinv.c  view on Meta::CPAN

PURPOSE:	Transforms input Easting and Northing to longitude and
		latitude for the Wagner IV projection.  The
		Easting and Northing must be in meters.  The longitude
		and latitude values will be returned in radians.

PROGRAMMER              DATE
----------              ----
D. Steinwand, EROS      May, 1991

This function was implemented with formulas supplied by John P. Snyder.

ALGORITHM REFERENCES

1.  Snyder, John P. and Voxland, Philip M., "An Album of Map Projections",
    U.S. Geological Survey Professional Paper 1453 , United State Government
    Printing Office, Washington D.C., 1989.

2.  Snyder, John P., Personal correspondence, January 1991.
*******************************************************************************/
#include "cproj.h"

gctpc/wviifor.c  view on Meta::CPAN

PURPOSE:	Transforms input longitude and latitude to Easting and
		Northing for the Wagner VII projection.  The
		longitude and latitude must be in radians.  The Easting
		and Northing values will be returned in meters.

PROGRAMMER              DATE            
----------              ----           
D. Steinwand, EROS      May, 1991     

This function was implemented with formulas supplied by John P. Snyder.
 
ALGORITHM REFERENCES

1.  Snyder, John P. and Voxland, Philip M., "An Album of Map Projections", 
    U.S. Geological Survey Professional Paper 1453 , United State Government 
    Printing Office, Washington D.C., 1989.

2.  Snyder, John P., Personal correspondence, January 1991.
*******************************************************************************/
#include "cproj.h"

gctpc/wviiinv.c  view on Meta::CPAN

		Easting and Northing must be in meters.  The longitude
		and latitude values will be returned in radians.

PROGRAMMER              DATE            
----------              ----           
D. Steinwand, EROS      May, 1991     
S. Nelson, EROS		Dec, 1993	Added function call to "asinz" to
					fix errors at 90 and -90 deg lat.
					This replaced calls to "asin".

This function was implemented with formulas supplied by John P. Snyder.
 
ALGORITHM REFERENCES

1.  Snyder, John P. and Voxland, Philip M., "An Album of Map Projections", 
    U.S. Geological Survey Professional Paper 1453 , United State Government 
    Printing Office, Washington D.C., 1989.

2.  Snyder, John P., Personal correspondence, January 1991.
*******************************************************************************/
#include "cproj.h"