help mata mm_ipolate()
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Title

    mm_ipolate() -- Linear interpolation


Syntax

        real colvector mm_ipolate(x, y, xnew)

        real colvector mm_ipolate(x, y, xnew, outer)


    where

                     x:  real colvector x
                     y:  real colvector y
                     x:  real colvector xnew
                 outer:  real scalar outer


Description

    mm_ipolate() assumes y to be piecewise linear in x and returns the linear
    interpolation of y at the values in xnew. Averages of y are used where x
    values are tied.

    outer!=0 specifies that the (average) y value corresponding to min(x)
    (max(x)) be returned for xnew values below (above) the support of x. The
    default is to return missing for xnew values that are outside the support
    of x.


Remarks

    Simple example:

        : x = (1 \ 2)

        : y = (10 \ 20)

        : mm_ipolate(x, y, 1.2)
          12


Conformability

    mm_ipolate(x, y, xnew, outer)
           x: n x 1
           y: n x 1
        xnew: r x 1
       outer: 1 x 1
      result: r x 1.


Diagnostics

    mm_ipolate() does not take any special action to treat missing values.


Source code

    mm_ipolate.mata


Author

    Ben Jann, ETH Zurich, jann@soz.gess.ethz.ch


Also see