Fortran toolkit
        
        
      varmeanfunction varmean(var,w,mask) result(meanvar)
  implicit none
  real(kind=8)            :: meanvar
  real(kind=8)            :: var(:)
  real(kind=8) , optional :: w(:)     
  logical      , optional :: mask(:)  
This function returns the mean of a variable var given some (optional) weights w. If supplied, the vector w should have the same size as var. If not supplied, the program assumes uniform weighting.
The user can also supply a mask to compute the conditional mean. The input mask is a logical array of the same size of var.
Dependencies: error
Example
mean = varmean(var,mask = var.gt.0.0d0 .and. var.lt.5.0d0)
This computes the mean of var conditional on var being between 0 and 5.