initial upload

src/volume_tri.f

@@ -0,0 +1,78 @@
+*dk volume_tri
+      subroutine volume_tri(x1,y1,z1,
+     *                      x2,y2,z2,
+     *                      x3,y3,z3,
+     *                      voltri)
+C
+C
+C#######################################################################
+C
+C      PURPOSE -
+C
+C         THIS ROUTINE FINDS THE VOLUME OF A TRI-ELEMENT DEFINDED BY
+C            3 COORDINATE NODES. THE VOLUME IS FOUND BY TAKING THE
+C            CROSS PRODUCT OF TWO VECTORS.
+C
+C
+C     ******************************************************************
+C
+C     DEFINE THE STRUCTURE OF A GENERIC TRIANGLE.
+C
+C            i3  *- - - - - -*  i2
+C                 \         /
+C                  \       /
+C                   \     /
+C                    \   /
+C                     \ /
+C                      *
+C                     i1
+C
+C     ******************************************************************
+C
+C      INPUT ARGUMENTS -
+C
+C        (x1,y1,z1),...,(x3,y3,z3) - THE COORDINATES OF THE TRI.
+C
+C     OUTPUT ARGUMENTS -
+C
+C        voltri - THE AREA OF THE TRI.
+C
+C     CHANGE HISTORY -
+C
+C        $Log: volume_tri.f,v $
+C        Revision 2.00  2007/11/09 20:04:06  spchu
+C        Import to CVS
+C
+CPVCS    
+CPVCS       Rev 1.2   Tue Oct 19 13:16:10 1999   jtg
+CPVCS    changed comment lines to actually correspond to a tri
+CPVCS    
+CPVCS       Rev 1.1   Mon Apr 14 17:05:44 1997   pvcs
+CPVCS    No change.
+CPVCS    
+CPVCS       Rev 1.0   Mon Jul 29 15:42:52 1996   dcg
+CPVCS    Initial revision.
+C
+C#######################################################################
+C
+C
+      implicit real*8 (a-h,o-z)
+C
+C#######################################################################
+C
+C
+C     ..................................................................
+C     TAKE THE CROSS PRODUCT OF THE 21 AND 31 VECTORS TO THE AN AREA
+C        VECTOR.
+C
+      dx= (y2-y1)*(z3-z1) - (y3-y1)*(z2-z1)
+      dy= (z2-z1)*(x3-x1) - (z3-z1)*(x2-x1)
+      dz= (x2-x1)*(y3-y1) - (x3-x1)*(y2-y1)
+C
+C     ..................................................................
+C     THEN TAKE 1/2 THE MAGNITUDE OF THIS AREA VECTOR TO GET THE TRI VOLUME
+C
+      voltri=0.5d+00*sqrt(dx**2+dy**2+dz**2)
+C
+      return
+      end