1
real*8 function evapol(tu,nu,tv,nv,c,rad,x,y)
2
c function program evacir evaluates the function f(x,y) = s(u,v),
3
c defined through the transformation
4
c x = u*rad(v)*cos(v) y = u*rad(v)*sin(v)
5
c and where s(u,v) is a bicubic spline ( 0<=u<=1 , -pi<=v<=pi ), given
6
c in its standard b-spline representation.
9
c f = evapol(tu,nu,tv,nv,c,rad,x,y)
12
c tu : real array, length nu, which contains the position of the
13
c knots in the u-direction.
14
c nu : integer, giving the total number of knots in the u-direction
15
c tv : real array, length nv, which contains the position of the
16
c knots in the v-direction.
17
c nv : integer, giving the total number of knots in the v-direction
18
c c : real array, length (nu-4)*(nv-4), which contains the
19
c b-spline coefficients.
20
c rad : real function subprogram, defining the boundary of the
21
c approximation domain. must be declared external in the
22
c calling (sub)-program
24
c before entry x and y must be set to the co-ordinates of
25
c the point where f(x,y) must be evaluated.
29
c on exit f contains the value of f(x,y)
31
c other subroutines required:
32
c bispev,fpbisp,fpbspl
35
c de boor c : on calculating with b-splines, j. approximation theory
37
c cox m.g. : the numerical evaluation of b-splines, j. inst. maths
38
c applics 10 (1972) 134-149.
39
c dierckx p. : curve and surface fitting with splines, monographs on
40
c numerical analysis, oxford university press, 1993.
44
c dept. computer science, k.u.leuven
45
c celestijnenlaan 200a, b-3001 heverlee, belgium.
46
c e-mail : Paul.Dierckx@cs.kuleuven.ac.be
48
c latest update : march 1989
50
c ..scalar arguments..
54
real*8 tu(nu),tv(nv),c((nu-4)*(nv-4))
55
c ..user specified function
59
real*8 u,v,r,f,one,dist
63
c ..function references
66
c calculate the (u,v)-coordinates of the given point.
71
if(dist.le.0.) go to 10
78
10 call bispev(tu,nu,tv,nv,c,3,3,u,1,v,1,f,wrk,8,iwrk,2,ier)