dev.nm.analysis.curvefit.interpolation.univariate

Class LinearInterpolation

java.lang.Object

dev.nm.analysis.curvefit.interpolation.univariate.LinearInterpolation

All Implemented Interfaces:

CurveFitting, Interpolation

public class LinearInterpolation
extends Object
implements Interpolation

(Piecewise-)Linear interpolation fits a curve by interpolating linearly between two adjacent data-points. For points on the curve which lie outside the data, the nearest segment is used (for extrapolation).

Fit once, then evaluate

Supply at least two data points with distinct x coordinates. SortedOrderedPairs provides an ordered representation. fit returns a function to evaluate at new x values. Outside the observed x range the nearest segment is extrapolated; values are not clamped to an endpoint.

Example

 import dev.nm.analysis.curvefit.interpolation.univariate.LinearInterpolation;
 import dev.nm.analysis.function.rn2r1.univariate.UnivariateRealFunction;
 import dev.nm.analysis.function.tuple.SortedOrderedPairs;

 SortedOrderedPairs points = new SortedOrderedPairs(
         new double[]{0, 1, 2}, new double[]{0, 2, 4});
 UnivariateRealFunction curve = new LinearInterpolation().fit(points);
 assert Math.abs(curve.evaluate(0.5) - 1.0) < 1e-12;
 assert Math.abs(curve.evaluate(3.0) - 6.0) < 1e-12; // extrapolation
 

See Also:

Wikipedia: Linear Interpolation

Constructor Summary

Constructors

Constructor and Description
LinearInterpolation()

Method Summary

Modifier and Type	Method and Description
UnivariateRealFunction	fit(OrderedPairs f) Fit a real valued function from a discrete set of data points.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LinearInterpolation

public LinearInterpolation()

Method Detail

fit

public UnivariateRealFunction fit(OrderedPairs f)

Description copied from interface: Interpolation

Fit a real valued function from a discrete set of data points.

The interpolated function must pass through all the given points.

Specified by:

fit in interface CurveFitting

Specified by:

fit in interface Interpolation

Parameters:

f - a discrete set of data points

Returns:

the interpolated function