没有内置的 Fortran 功能可以进行线性插值。您可以使用库或编写自己的例程。我没有尝试编译或测试，我的 fortran 可能有点生锈，但类似下面的东西应该可以工作。

subroutine interp1( xData, yData, xVal, yVal )
! Inputs: xData = a vector of the x-values of the data to be interpolated
!         yData = a vector of the y-values of the data to be interpolated
!         xVal  = a vector of the x-values where interpolation should be performed
! Output: yVal  = a vector of the resulting interpolated values

  implicit none

  real, intent(in) :: xData(:), yData(:), xVal(:)
  real, intent(out) :: yVal(:)
  integer :: inputIndex, dataIndex
  real :: minXdata, minYdata, xRange, weight

  ! Possible checks on inputs could go here
  ! Things you may want to check:
  !   monotonically increasing xData
  !   size(xData) == size(yData)
  !   size(xVal) == size(yVal)

  minXData = xData(1)
  maxXData = xData(size(xData))
  xRange = maxXData - minXData

  do inputIndex = 1, size(xVal)
      ! possible checks for out of range xVal could go here

      ! this will work if x is uniformly spaced, otherwise increment
      ! dataIndex until xData(dataIndex+1)>xVal(inputIndex)
      dataIndex = floor((xVal(inputIndex)-minXData)/xRange);

      weight = (xVal - xData(dataIndex))/(xData(dataIndex+1)-xData(dataIndex));
      yVal(inputIndex) = (1.0-weight)*yData(dataIndex) + ...
                         weight*yData(dataIndex+1);
  end do
end subroutine

看看这里的经典数字食谱书。查看插值章节。您可以找到解释以及代码。它是 pdf 格式的。一个简单的 google 搜索还产生了Thomas Robitaille 的github 库，其中存在一个名为 interp1d 的例程。