# LOOKUP

## Purpose:

Selects data points from one series according
to a "table" of point numbers contained in a second series.
The point values isolated by this method are then plotted in the current
Window.

## Syntax:

LOOKUP(series1 ,
series2 , factor, offset)

series1 |
- |
A series or table, containing point numbers
to be selected from series 2. Points in this series must be integers because
they refer to point numbers and not y-values. |

series2 |
- |
Any series, table, or expression evaluating
to a series or table. |

factor |
- |
Optional. A multiplicative factor for series
1, the "table" of point numbers. Defaults to 1.0. |

offset |
- |
Optional. An offset added to the table after
multiplying by the factor argument. Defaults to 0.0. |

## Returns:

A series or table.

## Example:

W1: gline(10, 0.1, 2, 1)

W2: {1, 2, 4, 5}

W3: lookup(W2, W1)

return the series {1,
1.2, 1.6, 1.8}. This is equivalent to using the array index syntax
W1[W2].

## Example:

lookup(W2, W1, 2, 1)

yields the series {1.4,
1.8, 2.6, 0.0}. The final 0.0 occurs because the fourth value in
the lookup table is 5 which, when multiplied by 2 and added to 1, yields
11. There is no 11th point in the target series, so the default y value
is 0.

## Remarks:

Use factor and offset arguments to adjust
the x-axis units.

## See Also:

GRADE

REORDER

SORT