Documentation

This is machine translation

Translated by Microsoft
Mouse over text to see original. Click the button below to return to the English verison of the page.

我们为许可用户提供了部分翻译好的中文文档。您只需登录便可查阅这些文档

Polynomial Curve Fitting

This example shows how to fit a polynomial curve to a set of data using polyfit. Use the polyfit function to find the coefficients of a polynomial that fits a set of data in a least-squares sense using the syntax

p = polyfit(x,y,n),

where:

  • x and y are vectors containing the x and y data to be fitted

  • n is the degree of the polynomial to return

Consider the x-y test data

x = [1 2 3 4 5];
y = [5.5 43.1 128 290.7 498.4];

Use polyfit to find a third-degree polynomial that approximately fits the data.

p = polyfit(x,y,3)
p =

   -0.1917   31.5821  -60.3262   35.3400

After you obtain the polynomial using polyfit, use polyval to evaluate the polynomial at other points that might not have been included in the original data.

Compute the values of the polyfit estimate over a finer domain and plot the estimate over the real data values for comparison.

x2 = 1:.1:5;
y2 = polyval(p,x2);
plot(x,y,'o',x2,y2)
grid on

See Also

|

More About


Was this topic helpful?