# Difference between revisions of "Documentation/How Tos/Calc: FORECAST function"

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## FORECAST

Fits a straight line to data using linear regression and returns a point on that line.

### Syntax:

FORECAST(new_xvalue; yvalues; xvalues)

yvalues and xvalues are single row or column ranges specifying points in a set of data. yvalues and xvalues must be the same size.
FORECAST fits a straight line through these data points, using the linear regression method.
FORECAST returns the y value on the straight line found, corresponding to the x value in new_xvalue. It is equivalent to TREND(yvalues; xvalues; new_xvalue).
Advanced topic:
The parameters xvalues and yvalues are always evaluated as array formulas. Note that TREND does not evaluate its parameters as array formulas.

### Example:

FORECAST(6; B2:B6; A2:A6)

where the x values in A2:A6 are 1, 2, 3, 4, 5 and the y values in B2:B6 are 2, 4, 7, 8, 11 returns 13.

TREND(B2:B6; A2:A6; 6)

with the same x values and y values, also returns 13.