//===========================================================================
// Copyright (C) 1998, 2000-2007, 2010, 2011, 2012 SINTEF ICT, Applied
// Mathematics, Norway.
//
// This file is part of GoTools
//
// This program is free software; you can redistribute it and/or          
// modify it under the terms of the GNU General Public License            
// as published by the Free Software Foundation version 2 of the License. 
//
// This program is distributed in the hope that it will be useful,        
// but WITHOUT ANY WARRANTY; without even the implied warranty of         
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          
// GNU General Public License for more details.                           
//
// You should have received a copy of the GNU General Public License      
// along with this program; if not, see <http://www.gnu.org/licenses>
//
// Contact information: E-mail: tor.dokken@sintef.no                      
// SINTEF ICT, Department of Applied Mathematics,                         
// P.O. Box 124 Blindern,                                                 
// 0314 Oslo, Norway.                                                     
//
// Other licenses are also available for this software, notably licenses
// for:
// - Building commercial software.                                        
// - Building software whose source code you wish to keep private.        
//===========================================================================

#include "sisl-copyright.h"

/*
 *
 * $Id: s1224.c,v 1.3 2005-02-28 09:04:48 afr Exp $
 *
 */


#define S1224

#include "sislP.h"
 


#if defined(SISLNEEDPROTOTYPES)
void 
   s1224(double et1[], double et2[], int ik1, int ik2, int in1, int in2, 
	 int ibase1, int ibase2, double par[], int ider, 
	 double ebder[], int *jstat)
#else
void s1224(et1, et2, ik1, ik2, in1, in2, ibase1, ibase2, par, ider, 
	   ebder, jstat)
     double et1[];
     double et2[];
     int    ik1;
     int    ik2;
     int    in1;
     int    in2;
     int    ibase1;
     int    ibase2;
     double par[];
     int    ider;
     double ebder[];
     int    *jstat;
#endif
/*
*********************************************************************
*
*********************************************************************
*                                                                   
* PURPOSE    : To compute the value and derivatives of the tensor product
*              B-spline base function starting at (et1[ibase1], et2[ibase2]), 
*              associated with the knot vectors et1 and et2, at the point par.
*
*
*
* INPUT      : et1    - Double array of dimension [in1+ik1] containing
*                       the knot vector in the first parameter direction.
*              et2    - Double array of dimension [in2+ik2] containing
*                       the knot vector in the second parameter direction.
*              ik1    - The polynomial order of the B-splines associated
*                       with et1.
*              ik2    - The polynomial order of the B-splines associated
*                       with et2.
*              in1    - The dimension of the spline space associated with
*                       the knot vector et1.
*              in2    - The dimension of the spline space associated with
*                       the knot vector et2.
*              ibase1 - The B-spline base function to evaluate (starting at
*                       et1[ibase1]), in the first parameter direction.
*              ibase2 - The B-spline base function to evaluate (starting at
*                       et2[ibase2]), in the second parameter direction.
*              par    - The point at which the tensor product B-spline value 
*                       and derivatives are to be computed.
*              ider  - The number of derivatives to be computed.
*                       < 0 : Error.
*                       = 0 : Compute position.
*                       = 1 : Compute position and first derivative.
*                       etc.
*                
*
* OUTPUT     : ebder  - Double array containing value of the tensor product
*                       B-spline and its derivatives at the point par. 
*                       The sequence is position, first derivative in first
*                       parameter direction, first derivative in second
*                       parameter direction, (2,0) derivative, (1,1) derivative,
*                       (0,2) derivative etc.
*                       The array has dimension (ider + 1)*(ider + 2)/2.
*              jstat  - Status messages  
*                                         > 0      : Warning.
*                                         = 0      : Ok.
*                                         < 0      : Error.
*
*
* METHOD     : 
*
* CALLS      : 
*
* WRITTEN BY : Johannes Kaasa, SINTEF, November 1995.
*
*********************************************************************
*/                                     
{
   int kstat=0;          /* Local status variable.                        */
   int kpos=0;           /* The position of the error.                    */
   int ki, kj, kl, kn;   /* Index in for loop.                            */
   int knumb1;           /* Necessary size of sder1.                      */
   int knumb2;           /* Necessary size of sder2.                      */
   double sdum1[100];    /* Fixed utility array.                          */
   double sdum2[100];    /* Fixed utility array.                          */
   double *sder1 = SISL_NULL; /* Evaluation in the first parameter direction.  */
   double *sder2 = SISL_NULL; /* Evaluation in the second parameter direction. */
   

   /* If necessary allocate space for the evaluation in each 
      parameter direction.                                   */
   
   knumb1 = ik1*(ider + 1);
   knumb2 = ik2*(ider + 1);
   
   if (knumb1 > 100)
   {
      if ((sder1 = newarray(knumb1, double)) == SISL_NULL)
	 goto err101;
   }
   else
      sder1 = &sdum1[0];
   
   if (knumb2 > 100)
   {
      if ((sder2 = newarray(knumb2, double)) == SISL_NULL)
	 goto err101;
   }
   else
      sder2 = &sdum2[0];
   
   /* Compute the value and derivatives in the first parameter direction. */
   
   s1222(et1, ik1, in1, ibase1, par[0], ider, sder1, &kstat);
   if (kstat < 0) goto error;

   /* Compute the value and derivatives in the second parameter direction. */
   
   s1222(et2, ik2, in2, ibase2, par[1], ider, sder2, &kstat);
   if (kstat < 0) goto error;
   
   /* Multiply together. */
   
   for (ki = 0, kl = 0; ki < (ider + 1); ki++)
   {
      for (kj = ki, kn = 0; kj > -1; kj--, kn++, kl++)
	 ebder[kl] = sder1[kj]*sder2[kn];
   }
   
   /* Successful computations.  */
   
   goto out;
   
   /* Not enough memory. */
   
   err101: 
      *jstat = -101;
   s6err("s1224",*jstat,kpos);
   goto out;
   
   /* Error in lower level routine.  */
   
   error:  
      *jstat = kstat;
   s6err("s1224",*jstat,kpos);
   goto out;
   
   out: 
      if (knumb1 > 100 && sder1 != SISL_NULL) freearray(sder1);
      if (knumb2 > 100 && sder2 != SISL_NULL) freearray(sder2);
      
      return;
}
