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Titanium test data


[x,y] = titanium


[x,y] = titanium returns measurements of a certain property of titanium as a function of temperature. Since their use in [1], these data have become a standard test for data fitting since they are hard to fit by classical techniques and have a significant amount of noise.


The plot of the data shown below is generated by the following commands:

[x,y] = titanium; plot(x,y,'ok'), set(gca,'Fontsize',16) 

The two-dimensional figure contains a sequence of points which increase and then decrease sharply.


[1] C. de Boor and J. R. Rice. "Least squares cubic spline approximation II - Variable knots." CSD TR 21, Comp.Sci., Purdue Univ., April 1968.