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Diffstat (limited to 'math/deboor/progs/prog4.f')
| -rw-r--r-- | math/deboor/progs/prog4.f | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/math/deboor/progs/prog4.f b/math/deboor/progs/prog4.f new file mode 100644 index 00000000..8fc73304 --- /dev/null +++ b/math/deboor/progs/prog4.f @@ -0,0 +1,35 @@ +chapter x. example 1. plotting some b-splines +c from * a practical guide to splines * by c. de boor +calls bsplvb, interv + integer i,j,k,left,leftmk,mflag,n,npoint + real dx,t(10),values(7),x,xl +c dimension, order and knot sequence for spline space are specified... + data n,k /7,3/, t /3*0.,2*1.,3.,4.,3*6./ +c b-spline values are initialized to 0., number of evaluation points... + data values /7*0./, npoint /31/ +c set leftmost evaluation point xl , and spacing dx to be used... + xl = t(k) + dx = (t(n+1)-t(k))/float(npoint-1) +c + print 600,(i,i=1,5) + 600 format(4h1 x,8x,5(1hb,i1,3h(x),7x)) +c + do 10 i=1,npoint + x = xl + float(i-1)*dx +c locate x with respect to knot array t . + call interv ( t, n, x, left, mflag ) + leftmk = left - k +c get b(i,k)(x) in values(i) , i=1,...,n . k of these, +c viz. b(left-k+1,k)(x), ..., b(left,k)(x), are supplied by +c bsplvb . all others are known to be zero a priori. + call bsplvb ( t, k, 1, x, left, values(leftmk+1) ) +c + print 610, x, (values(j),j=3,7) + 610 format(f7.3,5f12.7) +c +c zero out the values just computed in preparation for next +c evalulation point . + do 10 j=1,k + 10 values(leftmk+j) = 0. + stop + end |