chint.f90

来自「FORTRANvisualfortran常用数值算法集及源码」· F90 代码 · 共 18 行

SUBROUTINE chint(a,b,c,cint,n)
INTEGER n
REAL a,b,c(n),cint(n)
INTEGER j
REAL con,fac,sum
con=0.25*(b-a)
sum=0.
fac=1.
do j=2,n-1
  cint(j)=con*(c(j-1)-c(j+1))/(j-1)
  sum=sum+fac*cint(j)
  fac=-fac
end do
cint(n)=con*c(n-1)/(n-1)
sum=sum+fac*cint(n)
cint(1)=2.*sum
END SUBROUTINE chint