!向量卷积(valid模式，去掉补零边缘)
    !要求m>=n
    !z的大小 = m-n+1
    SUBROUTINE conv_valid(m,x,n,y,z)
    implicit none
    
    integer :: m,n
    real*8 :: x(m),y(n),z(m-n+1)
    
    real*8 :: temp(m+n-1)
    integer :: i,j
    
    !z = 0
    !do i=1,m-n+1
    !    do j=1,n
    !        z(i) = z(i)+x(i+j-1)*y(j)
    !    end do
    !end do
    
    z = 0
    temp = 0
    do i=1,m
        do j=1,n
            temp(i+j-1) = temp(i+j-1)+x(i)*y(j)
        end do
    end do
    
    z = temp(n:m)
    
    end subroutine