CRVLENGTH

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

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.

Syntax

Result = CRVLENGTH( X, Y [, /DOUBLE] )

Return Value

Returns the curve length.

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.

Keywords

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] 
 
;Compute the length of the curve: 
result = CRVLENGTH(x, y) 
 
Print, result 

IDL prints:

14.8115 

Version History

Introduced: 5.0

See Also

INT_TABULATED, PNT_LINE