[u/mrichter/AliRoot.git] / GEANT321 / ggeom / gvgrad.F

*
* $Id$
*
* $Log$
* Revision 1.1.1.1  1995/10/24 10:20:57  cernlib
* Geant
*
*
#include "geant321/pilot.h"
*CMZ :  3.21/02 29/03/94  15.41.31  by  S.Giani
*-- Author :
*
      SUBROUTINE GVGRAD (XYZ, C, NC, GRA)
************************************************************************
*                                                                      *
* GVGRAD calculates the gradient vector of a surface         VP 880314 *
*                                                                      *
* Input  : XYZ     coordinates of the point                            *
*          C(1)       number of non constant coefficients of the       *
*                        surface                                       *
*          C(2),C(3),... non constant coefficients of the surface      *
*          NC      total number of coefficients of the surface         *
*                                                                      *
* Output : GRA     gradient vector of the surface                      *
*                                                                      *
************************************************************************
      REAL           XYZ(3) , C(*), GRA(3)
*-----------------------------------------------------------------------
*
*     case with simplified surface X=C0, Y=C0, Z=C0, X*2+Y*2=C0
*     (happens only when initialisation is done)
*
      IF (NC.EQ.2)              THEN
        IAX = C(2)
        IF (IAX.LE.3)           THEN
          GRA(1) = 0
          GRA(2) = 0
          GRA(3) = 0
          GRA(IAX) = 1
        ELSE
          GRA(1)   = 2.*XYZ(1)
          GRA(2)   = 2.*XYZ(2)
          GRA(3)   = 0.
        ENDIF
        GO TO 999
      ENDIF
*
*     case with surfaces with 4, 7 or 10 coefficients (normal case)
*
      GRA(1) = C(2)
      GRA(2) = C(3)
      GRA(3) = C(4)
      IF (NC.EQ.4)              GO TO 999
*
*     case with surfaces with 7 or 10 coefficients
*
      DO 100 I = 1,3
  100   GRA(I) = GRA(I) + 2.*C(I+4)*XYZ(I)
      IF (NC.NE.10)             GO TO 999
*
*     case with surfaces with 10 coefficients
*
      GRA(1)   = GRA(1) + C(8)*XYZ(2)+C(10)*XYZ(3)
      GRA(2)   = GRA(2) + C(8)*XYZ(1)+C( 9)*XYZ(3)
      GRA(3)   = GRA(3) + C(9)*XYZ(2)+C(10)*XYZ(1)
 
  999 RETURN
      END
Commit	Line	Data
fe4da5cc	1	*
	2	* $Id$
	3	*
	4	* $Log$
	5	* Revision 1.1.1.1 1995/10/24 10:20:57 cernlib
	6	* Geant
	7	*
	8	*
	9	#include "geant321/pilot.h"
	10	*CMZ : 3.21/02 29/03/94 15.41.31 by S.Giani
	11	*-- Author :
	12	*
	13	SUBROUTINE GVGRAD (XYZ, C, NC, GRA)
	14	************************************************************************
	15	* *
	16	* GVGRAD calculates the gradient vector of a surface VP 880314 *
	17	* *
	18	* Input : XYZ coordinates of the point *
	19	* C(1) number of non constant coefficients of the *
	20	* surface *
	21	* C(2),C(3),... non constant coefficients of the surface *
	22	* NC total number of coefficients of the surface *
	23	* *
	24	* Output : GRA gradient vector of the surface *
	25	* *
	26	************************************************************************
	27	REAL XYZ(3) , C(*), GRA(3)
	28	*-----------------------------------------------------------------------
	29	*
	30	* case with simplified surface X=C0, Y=C0, Z=C0, X2+Y2=C0
	31	* (happens only when initialisation is done)
	32	*
	33	IF (NC.EQ.2) THEN
	34	IAX = C(2)
	35	IF (IAX.LE.3) THEN
	36	GRA(1) = 0
	37	GRA(2) = 0
	38	GRA(3) = 0
	39	GRA(IAX) = 1
	40	ELSE
	41	GRA(1) = 2.*XYZ(1)
	42	GRA(2) = 2.*XYZ(2)
	43	GRA(3) = 0.
	44	ENDIF
	45	GO TO 999
	46	ENDIF
	47	*
	48	* case with surfaces with 4, 7 or 10 coefficients (normal case)
	49	*
	50	GRA(1) = C(2)
	51	GRA(2) = C(3)
	52	GRA(3) = C(4)
	53	IF (NC.EQ.4) GO TO 999
	54	*
	55	* case with surfaces with 7 or 10 coefficients
	56	*
	57	DO 100 I = 1,3
	58	100 GRA(I) = GRA(I) + 2.C(I+4)XYZ(I)
	59	IF (NC.NE.10) GO TO 999
	60	*
	61	* case with surfaces with 10 coefficients
	62	*
	63	GRA(1) = GRA(1) + C(8)XYZ(2)+C(10)XYZ(3)
	64	GRA(2) = GRA(2) + C(8)XYZ(1)+C( 9)XYZ(3)
65	GRA(3) = GRA(3) + C(9)XYZ(2)+C(10)XYZ(1)
66
67	999 RETURN
68	END