Cubic spline interpolation function.

Syntax

New_y = Spline(Old_x, Old_y, New_x, Option)

Arguments

Name

Description

Old_x

A vector of the x data of the curve to be interpolated.

Old_y

A vector of the y data of the curve to be interpolated.

New_x

A vector containing x values for which new y values are to be calculated.

Option (optional)

Set to "extrap" to allow extrapolation when values of New_x are beyond the range of Old_x.  The default is "noextrap."

Output

Name

Description

New_y

A vector of the new y values at the given new x values.

Example

For a given pair of x values, find the corresponding cubic spline y values.

Syntax

Result

y =   2.42         20.48

Comments

When the length of Old_y equals the length of Old_x, the “knot a not” end conditions apply. When the length of Old_y is two greater than the length of Old_x, then the “clamped” end conditions apply, and the first and last values of Old_y are used as the first derivatives of the respective endpoints.

See Also:

MultiRegress

ExpFit

PolyFit