# CURVEINTERP is the jOceans module of jLab.

``` CURVEINTERP  Interpolate a field or its gradient onto a set of curves.

CURVEINTERP is a low-level function called by CLOSEDCURVES and
CURVEMOMENTS.

FC=CURVEINTERP(X,Y,F,XC,YC) interpolates the field in matrix F, with
axes X and Y, onto the curves specified by XC and YC.

X is associated with the *columns* of F and Y with its *rows*.  The
lengths of X and Y must match SIZE(F,2) and SIZE(F,1) respectively.

Unlike INTERP2, CURVEINTERP permits XC and YC to be cell arrays of
column vectors, in which case FC will be a cell array of the same size.
This is useful for working with CLOSEDCURVES and CURVEMOMENTS.

CURVEINTERP uses a fast loopless algorithm that is an order of
magnitude faster than looping over the individual curves.

CURVEINTERP works by calling INTERP2 with the 'linear' algorithm.
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F, but instead its *gradient*, and returns the result in the complex-

This can be very useful when F is large, because it is not necessary
to compute the gradient of F everywhere.  It is only computed locally
in near the curves, which can lead to a considerable speed improvment.
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