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added shank

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This commit is contained in:
Emmanuel Giner 2020-04-30 19:14:50 +02:00
parent 9737de21b7
commit b0823fe003
1 changed files with 39 additions and 0 deletions
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src/utils/shank.irp.f Normal file
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double precision function shank3_f(array,n,nmax)
implicit none
integer, intent(in) :: n,nmax
double precision, intent(in) :: array(0:nmax) ! array of the partial sums
integer :: ntmp
double precision :: shank1(0:nmax),shank2(0:nmax),shank3(0:nmax)
ntmp = n
call shank(array,ntmp,nmax,shank1)
ntmp = ntmp - 2
call shank(shank1,ntmp,nmax,shank2)
ntmp = ntmp - 2
call shank(shank2,ntmp,nmax,shank3)
ntmp = ntmp - 2
shank3_f = shank3(ntmp)
end
subroutine shank(array,n,nmax,shank1)
implicit none
integer, intent(in) :: n,nmax
double precision, intent(in) :: array(0:nmax)
double precision, intent(out) :: shank1(0:nmax)
integer :: i,j
double precision :: shank_function
do i = 1, n-1
shank1(i-1) = shank_function(array,i,nmax)
enddo
end
double precision function shank_function(array,i,n)
implicit none
integer, intent(in) :: i,n
double precision, intent(in) :: array(0:n)
double precision :: b_n, b_n1
b_n = array(i) - array(i-1)
b_n1 = array(i+1) - array(i)
shank_function = array(i+1) - b_n1*b_n1/(b_n1-b_n)
end