DERIVER

Name

deriver

Purpose (one Line)

Compute the step-wise derivative of a function of one variable.

Description

Calculates the step-wise derivative of a function by computing
deltaf / deltax. This requires that f and x be vectors with at least
two elements.
The uncertainties associated with the dependent variable of the
function may be supplied via a keyword, in which case the uncertainties
associated with the derivative are returned to the caller via another
keyword parameter.

Calling Sequence

deriver, x, f, newx, fprime, [, FERR=in_ferr, FPERR=out_fperr]

Inputs

x : Independent variable.
f : Dependent variable.

Optional Input Parameters

Keyword Parameters

FERR = Uncertainty in f (optional input).
FPERR = Uncertainty in fprime (optional output).

Outputs

newx : The centered x-values corresponding to fprime.
fprime : The computed derivative of the dependent variable.

Common Blocks

Side Effects

Restrictions

Procedure

Modification History

Written by Doug Loucks, Lowell Observatory, July, 1993.
1999 Nov 24, Marc W. Buie, Lowell Observatory, changed name to eliminate
a naming conflict with DERIVE, an IDL built-in routine.