Example of Interpolation and extrapolation:

The MATLAB has a function to do this, known as polyfit. The function polyfit finds the coefficients of the polynomial of the particular degree which best fits the data by using a least squares algorithm. There are 3 arguments passed to the function: the vectors which represent the data, and the degree of the preferred polynomial. For illustration, to fit a straight line (degree 1) through the earlier data points, the call to the polyfit function would be:

>> polyfit(x,y,1)

ans =

   0.0000 67.6000

that says that the best straight line is of the form 0x + 67.6. Though, from the plot as shown in figure, it appears like a quadratic would be a much better fit. The following would generate the vectors and then fit a polynomial of degree 2 through the data points, storing the values in a vector known as coefs.

>> x = 2:6;

>> y = [65 67 72 71 63];

>> coefs = polyfit(x,y,2)

coefs =

   -1.8571 14.8571 41.6000

This says that the MATLAB has determined that the best quadratic which fits these data points are:

-1.8571x²  + 14.8571x + 41.6. So, the variable coefs now stores a vector which represents this polynomial.

Posted Date: 10/22/2012 8:45:55 AM | Location : United States

Ask an Expert

Related Discussions:- Example of interpolation and extrapolation, Assignment Help, Ask Question on Example of interpolation and extrapolation, Get Answer, Expert's Help, Example of interpolation and extrapolation Discussions

Write discussion on Example of interpolation and extrapolation
Your posts are moderated

Write your message here..

Related Questions

Sort algorithm for sorting vectors of structures, Sort algorithm for Sortin... Sort algorithm for Sorting vectors of structures: Note that only the price field is compared in the sort algorithm, but the whole structure is replaced. That is therefore each

Calcrectarea subfunction, calcrectarea subfunction: function call: ar... calcrectarea subfunction: function call: area = calcrectarea(len,wid); function header: function area = calcrectarea(len, wid)   In the function call, the two arg

Appending variables to the mat-file, Appending variables to the Mat-File: ... Appending variables to the Mat-File: Appending to the file adds to what has been saved in a file, and is accomplished by using the -append option. For illustration, supposing

Tracing of square matrices, Tracing of Square matrices: The trace of a... Tracing of Square matrices: The trace of a square matrix is the addition of all the elements on the diagonal. For illustration, for the preceding matrix it is 1 + 6 + 11 + 16,

Use of nested if-else statements, Use of Nested if-else statements: By... Use of Nested if-else statements: By using the nested if-else to select from among the three possibilities, not all the conditions should be tested. In this situation, if x is

Finding a sting - function strfind, Finding a sting - function strfind: ... Finding a sting - function strfind: The function strfind does necessarily similar thing, except that the order of the arguments does make dissimilarity. The common form is str

Illustration of initializing the data structure, Illustration of initializi... Illustration of initializing the data structure: illustration of initializing the data structure by preallocating is here as shown: >> cyls(3) = struct('code', 'c', 'dimen

Chapter 7 , 7.13 7.13

Sampling theorem, about sampling theorem about sampling theorem

Execution steps - modular program, Execution steps: Whenever the progr... Execution steps: Whenever the program is executed, the steps below will take place: The script calcandprintarea starts executing. The calcandprintarea calls the readr