CRVLENGTH

The CRVLENGTH function computes the length of a curve with a tabular representation, Y [ i ] = F( X [ i ]).

CAUTION: Data that is highly oscillatory requires a sufficient number of samples for an accurate curve length computation.

This routine is written in the IDL language. Its source code can be found in the file crvlength.pro in the lib subdirectory of the IDL distribution.

Calling Sequence

Result = CRVLENGTH( X , Y )

Arguments

X

An n -element single- or double-precision floating-point vector. X must contain at least three elements, and values must be specified in ascending order. Duplicate X values will result in a warning message.

Y

An n -element single- or double-precision floating-point vector.

Keyword

DOUBLE

Set this keyword to force the computation to be done in double-precision arithmetic.

Example

Define a 21-element vector of X -values.

x = [-2.00, -1.50, -1.00, -0.50, 0.00, 0.50, 1.00, 1.50, 2.00, $

2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, $

7.00, 7.50, 8.00]

Define a 21-element vector of Y -values.

y = [-2.99, -2.37, -1.64, -0.84, 0.00, 0.84, 1.64, 2.37, 2.99, $

3.48, 3.86, 4.14, 4.33, 4.49, 4.65, 4.85, 5.13, 5.51, $

6.02, 6.64, 7.37]

result = CRVLENGTH(x, y) ; Compute the length of the curve .

Print, result ; Print result.

IDL prints:

14.8115