# DERIV

## Purpose:

Calculates the derivative of a series.

## Syntax:

DERIV(series)

 series - An interval or XY series, the series to differentiate.

## Returns:

A series or table.

## Example:

W1: {1, 3, 2, 7}

W2: deriv(w1)

W2 contains the derivative with values {2, 0.5, 2, 5} representing the slope of W1 at each point.

## Example:

W1: gsin(1000,.001)

W2: xy(xvals(w1), yvals(w1))

W3: deriv(w1)

W4: deriv(w2)

W5: w3 - w4

W1 contains a 1 Hertz sinewave over one period as an interval series. W2 converts W1 into an XY series. The X values of W1 are implicit and can be constructed from the delta X value. The X values of W2 are explicit.

The derivatives of each series are calculated and the differences are displayed in W5.

## Remarks:

DERIV calculates the derivative of evenly spaced (interval series) or unevenly spaced (XY series) data by taking the points at n-1, n, and n+1, finding the quadratic curve to fit those three points and returns the slope of the curve at point n as the derivative of the series at point n.

See  LDERIV and RDERIV for 2 point derivative methods.

See FDERIV for an implementation in the frequency domain.

See DIFF to compute the series difference.

DIFF

DYDX

FDERIV

INTEG

LDERIV

RDERIV