interpol

The interpol function executes a linear interpolation or cosine interpolation for the given x-coordinates.

rvYi = interpol(rvX, rvY, rvXi)

rvYi = interpol(rvX, rvY, rvXi, rsMissing)

rvYi = interpol(rvX, rvY, rvXi, rsMissing, ssType)

Return Value

rvYi

Parameters

rvX

rvX is a real vector with at least 2 elements. The coordinates must be sorted monoton increasing or decreasing.

rvY

rvY is a real vector with at least 2 elements. The number of points must be identical with rvX.

rvXi

rvXi is a real vector with at least one point.

rsMissing

1.) Values in rvYi >= rsMissing will be ignored in the interpolation. All elements in rvYi will be set to missing for rvYi >= rsMissing.

2.) If an extrapolation is necessary, the extrapolated values in rvYi are set to rsMissing. Default value is 0.

ssType

ssType is a string with the text linear or cosine. Default value is linear.

Example

x = [1,3,5,8]
y = [0,5,8,2]
h = plot(x,y)
yi = interpol(x, y, xi = linspace(1, 8, 5));
h = plot(xi, yi, h[2])
XYSetProps(h[3], "marker='1' marker-style='circle' curve-style='dash'");

x = [1,3,5,8]
y = [0,5,8,2]
h = plot(x,y)
yi = interpol(x, y, xi = linspace(1, 8, 5));
h = plot(xi, yi, h[2], 1e10, "cosine")
XYSetProps(h[3], "marker='1' marker-style='circle' curve-style='dash'");

If an error occures interpol returns an error object (see error_create).

x = [1,3,4, 5,8]
y = [0,5,8,2]
yi = interpol(x, y, [1,2,2]);
if (type(yi) == "error") {
    print yi.message;
}

History

Version	Description
R2018.12	New parameter ssType
4.2.4	rvXi can be non-monotonic.
4.2.0	New

See also

Overview Mathematic, fspline, pspline, rspline, akimaspline

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