Timur A. Fatkhullin
5279d1c41a
start developing of FITPACK C++ bindings mount_server.cpp: fix compilation error with GCC15
83 lines
2.3 KiB
Fortran
83 lines
2.3 KiB
Fortran
recursive subroutine fpchep(x,m,t,n,k,ier)
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implicit none
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c subroutine fpchep verifies the number and the position of the knots
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c t(j),j=1,2,...,n of a periodic spline of degree k, in relation to
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c the number and the position of the data points x(i),i=1,2,...,m.
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c if all of the following conditions are fulfilled, ier is set
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c to zero. if one of the conditions is violated ier is set to ten.
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c 1) k+1 <= n-k-1 <= m+k-1
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c 2) t(1) <= t(2) <= ... <= t(k+1)
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c t(n-k) <= t(n-k+1) <= ... <= t(n)
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c 3) t(k+1) < t(k+2) < ... < t(n-k)
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c 4) t(k+1) <= x(i) <= t(n-k)
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c 5) the conditions specified by schoenberg and whitney must hold
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c for at least one subset of data points, i.e. there must be a
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c subset of data points y(j) such that
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c t(j) < y(j) < t(j+k+1), j=k+1,...,n-k-1
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c ..
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c ..scalar arguments..
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integer m,n,k,ier
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c ..array arguments..
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real*8 x(m),t(n)
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c ..local scalars..
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integer i,i1,i2,j,j1,k1,k2,l,l1,l2,mm,m1,nk1,nk2
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real*8 per,tj,tl,xi
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c ..
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k1 = k+1
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k2 = k1+1
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nk1 = n-k1
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nk2 = nk1+1
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m1 = m-1
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ier = 10
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c check condition no 1
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if(nk1.lt.k1 .or. n.gt.m+2*k) go to 130
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c check condition no 2
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j = n
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do 20 i=1,k
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if(t(i).gt.t(i+1)) go to 130
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if(t(j).lt.t(j-1)) go to 130
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j = j-1
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20 continue
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c check condition no 3
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do 30 i=k2,nk2
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if(t(i).le.t(i-1)) go to 130
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30 continue
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c check condition no 4
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if(x(1).lt.t(k1) .or. x(m).gt.t(nk2)) go to 130
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c check condition no 5
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l1 = k1
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l2 = 1
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do 50 l=1,m
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xi = x(l)
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40 if(xi.lt.t(l1+1) .or. l.eq.nk1) go to 50
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l1 = l1+1
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l2 = l2+1
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if(l2.gt.k1) go to 60
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go to 40
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50 continue
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l = m
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60 per = t(nk2)-t(k1)
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do 120 i1=2,l
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i = i1-1
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mm = i+m1
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do 110 j=k1,nk1
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tj = t(j)
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j1 = j+k1
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tl = t(j1)
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70 i = i+1
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if(i.gt.mm) go to 120
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i2 = i-m1
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if (i2.le.0) go to 80
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go to 90
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80 xi = x(i)
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go to 100
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90 xi = x(i2)+per
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100 if(xi.le.tj) go to 70
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if(xi.ge.tl) go to 120
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110 continue
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ier = 0
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go to 130
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120 continue
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130 return
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end
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