# DYDX

## Purpose:

Calculates the derivative of XY data.

## Syntax:

DYDX(ysig, xsig)

ysig |
- |
An input XY series. |

xsig |
- |
Optional. A series, the explicit X values. |

## Returns:

An XY series.

## Example:

W1: xy(gexp(100,.01), gline(100,.01, 1, 0))

W2: dydx(W1);

W2 contains the first derivative of the XY data in W1.

## Example:

W3: dydx(gline(100, .01, 1, 0), gexp(100, .01))

Same as above except the Y and X series are explicit.

## Example:

W1: gsin(100, 1/100, 1);

W2: dydx(w1);

W3: rderiv(w1)

W2 contains the first derivative of the interval data in W1. W2 is identical
to W1 except for the last point.

## Remarks:

DYDX computes the 2 point right derivative of an XY or interval series.
The 2 point right derivative for a series **s**
is defined as:

DYDX is identical to the built-in RDERIV
function except for the last point. For a series of *N* points, the last point is computed as:

and for RDERIV:

See DERIV for a more sophisticated
algorithm.

See DIFF to compute the series difference.

## See Also:

DERIV

DIFF

FDERIV

INTEG

LDERIV

RDERIV