usvs_to_uv: update for zbeta

ChangeLog

-2006-11-??  Uwe Schulzweida  <Uwe.Schulzweida@zmaw.de>
+2006-11-30  Uwe Schulzweida  <Uwe.Schulzweida@zmaw.de>
 
         * using GRIB library version 1.0.4
 	* cdfInqContents: use grid_mapping not for curvilinear grids
 	* add env IGNORE_ATT_COORDINATES to ignore attribute coordinates
 	* splitBasetime: convert timeunit string to lower case
+	* usvs_to_uv: update for zbeta [from: Klaus Wyser]
 	* new function: vlistInqVarSzip
 	* new function: streamNvals
 	* Version 1.0.4 released

src/grid_rot.c

@@ -179,8 +179,7 @@ void usvs_to_uv(double us, double vs, double phi, double rla,
   */
   zbeta = fabs(acos(zarg));
   /*  if ( -(rla - (pollamd-180.0)) < 0 ) zbeta = -zbeta;*/
-  /*  if ( -(rla - (pollamd-180.0)) < 0 && !(rla > pollamd && rla < 180) ) zbeta = -zbeta;*/
-  if ( rla > pollamd-180 && rla <= pollamd ) zbeta = -zbeta;
+  if ( (-(rla - (pollamd-180.0)) < 0) && (-(rla - (pollamd-180.0)) >= -180) ) zbeta = -zbeta;
 
   /* us - wind transformieren */
   *u = us*cos(zbeta) - vs*sin(zbeta);