Численное интегрирование. (Фортран)
Beloshenko + 2007
-------------------------- Use common -------------------------------------
main.for
integer N
common /P/ N,x0,x1,sumL,sumR,sumTrap,sumMiddle
real*4 x0,x1
real*4 sumL,sumR,sumTrap,sumMiddle
open(unit=1, file='IntRes.txt', status='OLD')
N=5000
x0=0
x1=1.570796
call Obchisl
write(1,2)sumL,sumR,sumTrap,sumMiddle
2 format(F 8.5, 2X, F 8.5, 2X, F 8.5, 2X F 8.5)
close(1)
end
subrout.for
subroutine Obchisl
common /P/ N,x0,x1,sumL,sumR,sumTrap,sumMiddle
integer i
double precision xi,xi1
double precision delta
xi=x0
xi1=0
sumL=0
sumR=0
sumTrap=0
sumMiddle=0
delta=(x1-x0)/N
do 1 i=1,N-1
xi1=xi+delta
sumL=sumL+sin(xi1)
sumMiddle=sumMiddle+sin(xi1-delta/2)
xi=xi1
1 continue
sumMiddle=(sumMiddle+sin(x1-delta/2))*delta
sumR=sumL
sumTrap=sumL
sumL=sumL+sin(x0)
sumR=sumR+sin(x1)
sumL=((x1-x0)/N)*sumL
sumR=((x1-x0)/N)*sumR
sumTrap=(2*sumTrap+sin(x0)+sin(x1))*(x1-x0)/(2*N)
return
end
IntRes.txt
0.99984 1.00016 1.00000 1.00000
