SYNOPSISFUNCTION CURVD (T, N, X, Y, YP, SIGMA)
This function calculates a derivative at a specified point using a spline under tension. CURV1 must be called prior to calling CURVD, and the values thus obtained used as input to CURVD. The derivative value is returned.
- (real, input) The abscissa for which an interpolated function value is desired.
- (integer, input) The number of input data values. (N > 1)
- (real, input) An array containing the abscissae for the input function.
- (real, input) An array containing the functional values of the input data -- Y(K) is the functional value at X(K) for K=1,N.
- (real, input) Contains values for the second derivative (as calculated by CURV1).
- (real, input) Tension factor. Values near zero result in a cubic spline; large values (e.g. 50) result in nearly a polygonal line. A typical value is 1.
RETURN VALUECURVD returns the derivative value of the interpolated curve at the specified point T.
ACCESSTo use CURVD, load the NCAR Graphics library ngmath.
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University Corporation for Atmospheric Research
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