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# interp2Scattered

## PURPOSE

INTERP2SCATTERED - Interpolate scattered data at individual points.

## SYNOPSIS

function ZI = interp2Scattered( x, y, z, XI, YI, method, tri )

## DESCRIPTION

``` INTERP2SCATTERED - Interpolate scattered data at individual points.

This function interpolates scattered data at individual points.  It
uses delaunay triangulation and linear interpolation.  It is not unlike
interp2, except that the XI and YI don't have to be matrices.  They can
be vectors of points with no particular ordering.

Usage: ZI = interp2Scattered( x, y, z, XI, YI )
ZI = interp2Scattered( x, y, z, XI, YI, method )
ZI = interp2Scattered( x, y, z, XI, YI, method, tri )

Currently method can be one of two strings: 'linear' (the default),
'nearest'.  Linear is two dimensional linear interpolation with
triangles.  nearest is just nearest neighbor interpolation.  There is
also an 'old' method, which is the original algorithm I used which
calculates the normals.  This method does not always pass through the
data points if NaN's are present and is discouraged.

tri specifies the triangulation to use.  If left off or empty, delaunay
will be used.  This argument is principally for repeated faster calls to
interp2Scattered.  If given, no checking will be done for identical x-y
pairs.

This function basically copies the methods used in griddata - a ripoff.
That is why it is NOT GPL licensed.  The

Note: colinear data could screw up this calculation.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\$Id: interp2Scattered.m,v 1.8 2002-08-13 00:09:05 dmk Exp \$

Copyright (C) 2001 David M. Kaplan
Copyright 1984-2001 The MathWorks, Inc. (parts from griddata function).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%```

## CROSS-REFERENCE INFORMATION

This function calls:
• end END - basic end method for HFRC objects.
• isempty
• isnan ISNAN - returns position of any NaN data in either U or V.
• length LENGTH - returns number of times in HFRC object.
• mean MEAN - mean of a field in an HFRC object
• nearest NEAREST - Finds the grip points closest to a series of other points.
• size SIZE - returns [ (num times), (num gridpts) ].
This function is called by:

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