1 files changed, 46 insertions, 0 deletions
diff --git a/src/cmd/map/libmap/lambert.c b/src/cmd/map/libmap/lambert.c
new file mode 100644
index 00000000..6b688aa3
--- /dev/null
+++ b/src/cmd/map/libmap/lambert.c
@@ -0,0 +1,46 @@
+#include <u.h>
+#include <libc.h>
+#include "map.h"
+
+static struct coord stdp0, stdp1;
+static double k;
+
+static int
+Xlambert(struct place *place, double *x, double *y)
+{
+	double r;
+	if(place->nlat.l < -80.*RAD)
+		return(-1);
+	if(place->nlat.l > 89.*RAD)
+		r = 0;	/* slovenly */
+	else
+		r = stdp0.c*exp(0.5*k*log(
+		   (1+stdp0.s)*(1-place->nlat.s)/((1-stdp0.s)*(1+place->nlat.s))));
+	if(stdp1.l<0.)
+		r = -r;
+	*x = - r*sin(k * place->wlon.l);
+	*y = - r*cos(k * place->wlon.l);
+	return(1);
+}
+
+proj
+lambert(double par0, double par1)
+{
+	double temp;
+	if(fabs(par0)>fabs(par1)){
+		temp = par0;
+		par0 = par1;
+		par1 = temp;
+	}
+	deg2rad(par0, &stdp0);
+	deg2rad(par1, &stdp1);
+	if(fabs(par1+par0)<.1) 
+		return(mercator());
+	if(fabs(par1-par0)<.1)
+		return(perspective(-1.));
+	if(fabs(par0)>89.5||fabs(par1)>89.5)
+		return(0);
+	k = 2*log(stdp1.c/stdp0.c)/log(
+		(1+stdp0.s)*(1-stdp1.s)/((1-stdp0.s)*(1+stdp1.s)));
+	return(Xlambert);
+}