program spline
use BSINT_INT
use BSNAK_INT
use BSCPP_INT
use PPVAL_INT
use BSVAL_INT
implicit none
real(8) f
real(8) :: xi1=0.0d0, xi2=2.0d0
integer, parameter :: korder=4, ndata=20, ncoef=20, nknot=korder+ncoef
real(8) :: break(ncoef), ppcoef(korder,ncoef), bscoef(ncoef)
real(8), dimension(nknot) :: xknot
integer i,nppcf
real(8) x, xdata(ndata), fdata(ndata)
real(8) z1,z2,z3
real(8), parameter :: Pi=3.141592653589793238d0
f(x)=dsin(Pi/2.d0*x)
do i=1, ndata
x=xi1+(xi2-xi1)*dfloat(i-1)/dfloat(ndata-1)
xdata(i) = x
fdata(i) = f(x)
enddo
CALL D_BSNAK (NDATA, XDATA, KORDER, XKNOT)
CALL D_BSINT (NCOEF, XDATA, FDATA, KORDER, XKNOT, BSCOEF)
CALL D_BSCPP (KORDER, XKNOT, NCOEF, BSCOEF, NPPCF, BREAK, PPCOEF)
! Первый блок
I=2*ndata-3
x = dFLOAT(I)/dFLOAT(NDATA-1)
z1=f(x)
z2=D_BSVAL(x,KORDER,XKNOT,NCOEF,BSCOEF)
z3=D_PPVAL(x,BREAK,PPCOEF)
print*,'x=',x
print*,z1,' ',z2,' ',z3
print*
! Второй блок
x = dFLOAT(2*ndata-3)/dFLOAT(NDATA-1)
z1=f(x)
z2=D_BSVAL(x,KORDER,XKNOT,NCOEF,BSCOEF)
z3=D_PPVAL(x,BREAK,PPCOEF)
print*,'x=',x
print*,z1,' ',z2,' ',z3
print*
! Третий блок
I=2*ndata-3
x = dFLOAT(I)/dFLOAT(NDATA-1)
z1=f(x)
z2=D_BSVAL(x,KORDER,XKNOT,NCOEF,BSCOEF)
z3=D_PPVAL(x,BREAK,PPCOEF)
print*,'x=',x
print*,z1,' ',z2,' ',z3
print*
pause 'FINISH: press ENTER.'
end program spline
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