Generating Multivariate Polynomial Coeffients with known Constants
7 views (last 30 days)
Show older comments
I am extremely new to MatLab and am having a hard time trying to generate Coefficients from this equation:
t= (A * a) + (B * s) + (C * s * a)+ (D * s^2) + (E * s^2 * a) + (F)
I have the data for t,s,a.
Trying to find (A,B,C,D,E,F)
I can remove the Coefficient (F) if need be, being it is just an offset, and I have (t).
I could post what I have tried, but I usually dont save it because I am not getting close.
I do have Curve Fitting, Statistics, and Optimization Toolboxes thinking it would help.
I have also tried polyfit and polyfitn.
Also, if this has been answered a hundred times, what would best describe that equation for searching?
0 Comments
Accepted Answer
Steven Lord
on 2 Jul 2024
See the Multiple Regression section on this documentation page for an example you can adapt to your equation. Make sure you use array operators when constructing the columns of the design matrix.
7 Comments
Steven Lord
on 3 Jul 2024
If you use more information (and so more equations) that will also affect the solution. To use Cleve's example, if I told you that the two numbers have an average of 3 there are multiple solutions (3 and 3, 4 and 2, 6 and 0, etc.)
A = [1/2 1/2; 1 -1];
b = [3; 2];
solutionsToFirstEquation = [3 4 6 16-pi; 3 2 0 -10+pi]
checkFirstEquation = A(1, :)*solutionsToFirstEquation
If I then add the additional information that the difference of the two numbers is 2 the solution is unique. The solution is the second column of solutionsToFirstEquation.
x = A\b
satisfiesBothEquations = A*solutionsToFirstEquation % Only 2nd is right
satisfiesBothEquations2 = [A*x, b]
More Answers (0)
See Also
Categories
Find more on Least Squares in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!