Fortran toolkit

Borja Petit

varvar

function varvar(var,w,mask) result(variance)
  implicit none
  real(kind=8)            :: variance
  real(kind=8)            :: var(:)
  real(kind=8) , optional :: w(:)   
  logical      , optional :: mask(:)

This function returns the variance 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 variance. The input mask is a logical array of the same size of var.

Dependencies: error, varmean

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Example

variance = varvar(var,mask = var.gt.0.0d0 .and. var.lt.5.0d0)

This computes the variance of var conditional on var being between 0 and 5.