fortran：用梯形法计算定积分

刚学fortran的菜鸟
声明那里总是弄不对
求大神指点
详细题目在图片里

program for implicit none real :: a=0 real :: b=2 real,external :: hanshu write(*,*)hanshu(a,b)end programfunction hanshu(a,b) implicit none real ::a,b real :: hanshu real s=0.0 real h integer i integer,parameter :: n=20 real,parameter :: fo=4 real,parameter :: se=7 real hanshui h=(b-a)/n hanshu=0.0 do i=1,n hanshui = fo*(x+(i-1)*h)**2+fo*(x+(i-1)*h)+se+fo*(x+i*h)**2+fo*(x+ih)+se hanshu=hanshu+hanshui returnend
我只写出这么多