...

fitpack/bispev.f

@@ -0,0 +1,104 @@
+      recursive subroutine bispev(tx,nx,ty,ny,c,kx,ky,x,mx,y,my,z,
+     *    wrk,lwrk,iwrk,kwrk,ier)
+      implicit none
+c  subroutine bispev evaluates on a grid (x(i),y(j)),i=1,...,mx; j=1,...
+c  ,my a bivariate spline s(x,y) of degrees kx and ky, given in the
+c  b-spline representation.
+c
+c  calling sequence:
+c     call bispev(tx,nx,ty,ny,c,kx,ky,x,mx,y,my,z,wrk,lwrk,
+c    * iwrk,kwrk,ier)
+c
+c  input parameters:
+c   tx    : real array, length nx, which contains the position of the
+c           knots in the x-direction.
+c   nx    : integer, giving the total number of knots in the x-direction
+c   ty    : real array, length ny, which contains the position of the
+c           knots in the y-direction.
+c   ny    : integer, giving the total number of knots in the y-direction
+c   c     : real array, length (nx-kx-1)*(ny-ky-1), which contains the
+c           b-spline coefficients.
+c   kx,ky : integer values, giving the degrees of the spline.
+c   x     : real array of dimension (mx).
+c           before entry x(i) must be set to the x co-ordinate of the
+c           i-th grid point along the x-axis.
+c           tx(kx+1)<=x(i-1)<=x(i)<=tx(nx-kx), i=2,...,mx.
+c   mx    : on entry mx must specify the number of grid points along
+c           the x-axis. mx >=1.
+c   y     : real array of dimension (my).
+c           before entry y(j) must be set to the y co-ordinate of the
+c           j-th grid point along the y-axis.
+c           ty(ky+1)<=y(j-1)<=y(j)<=ty(ny-ky), j=2,...,my.
+c   my    : on entry my must specify the number of grid points along
+c           the y-axis. my >=1.
+c   wrk   : real array of dimension lwrk. used as workspace.
+c   lwrk  : integer, specifying the dimension of wrk.
+c           lwrk >= mx*(kx+1)+my*(ky+1)
+c   iwrk  : integer array of dimension kwrk. used as workspace.
+c   kwrk  : integer, specifying the dimension of iwrk. kwrk >= mx+my.
+c
+c  output parameters:
+c   z     : real array of dimension (mx*my).
+c           on successful exit z(my*(i-1)+j) contains the value of s(x,y)
+c           at the point (x(i),y(j)),i=1,...,mx;j=1,...,my.
+c   ier   : integer error flag
+c    ier=0 : normal return
+c    ier=10: invalid input data (see restrictions)
+c
+c  restrictions:
+c   mx >=1, my >=1, lwrk>=mx*(kx+1)+my*(ky+1), kwrk>=mx+my
+c   tx(kx+1) <= x(i-1) <= x(i) <= tx(nx-kx), i=2,...,mx
+c   ty(ky+1) <= y(j-1) <= y(j) <= ty(ny-ky), j=2,...,my
+c
+c  other subroutines required:
+c    fpbisp,fpbspl
+c
+c  references :
+c    de boor c : on calculating with b-splines, j. approximation theory
+c                6 (1972) 50-62.
+c    cox m.g.  : the numerical evaluation of b-splines, j. inst. maths
+c                applics 10 (1972) 134-149.
+c    dierckx p. : curve and surface fitting with splines, monographs on
+c                 numerical analysis, oxford university press, 1993.
+c
+c  author :
+c    p.dierckx
+c    dept. computer science, k.u.leuven
+c    celestijnenlaan 200a, b-3001 heverlee, belgium.
+c    e-mail : Paul.Dierckx@cs.kuleuven.ac.be
+c
+c  latest update : march 1987
+c
+c  ..scalar arguments..
+      integer nx,ny,kx,ky,mx,my,lwrk,kwrk,ier
+c  ..array arguments..
+      integer iwrk(kwrk)
+      real*8 tx(nx),ty(ny),c((nx-kx-1)*(ny-ky-1)),x(mx),y(my),z(mx*my),
+     * wrk(lwrk)
+c  ..local scalars..
+      integer i,iw,lwest
+c  ..
+c  before starting computations a data check is made. if the input data
+c  are invalid control is immediately repassed to the calling program.
+      ier = 10
+      lwest = (kx+1)*mx+(ky+1)*my
+      if(lwrk.lt.lwest) go to 100
+      if(kwrk.lt.(mx+my)) go to 100
+      if (mx.lt.1) go to 100
+      if (mx.eq.1) go to 30
+      go to 10
+  10  do 20 i=2,mx
+        if(x(i).lt.x(i-1)) go to 100
+  20  continue
+  30  if (my.lt.1) go to 100
+      if (my.eq.1) go to 60
+      go to 40
+  40  do 50 i=2,my
+        if(y(i).lt.y(i-1)) go to 100
+  50  continue
+  60  ier = 0
+      iw = mx*(kx+1)+1
+      call fpbisp(tx,nx,ty,ny,c,kx,ky,x,mx,y,my,z,wrk(1),wrk(iw),
+     * iwrk(1),iwrk(mx+1))
+ 100  return
+      end