Comparing least square equations in matlab

In summary: Type] = loglog_ls2_xxx(x,y);if e*f < bestFit bestFit = e*f; type = fitType;endIn summary, the function should accept input arrays x and y and use linear, semilogy, and log-log least squares fits to determine the best fit, which is determined by the smallest value. There are individual scripts for each equation, but the function compares them in Matlab and returns the type of equation with the best fit.
  • #1
honda221
1
0
The function should accept the input arrays x and y and to process the data using
linear, semilogy, and log‐log least squares fits to determine which is the best. For this problem, the "best" is given by the smallest value. I wrote the individual scripts for each for the different equations, but I wasn't sure how to compare them to each other in Matlab. Any help would be appreciated!

[a,b,type] = linear_ls2_xxx(x,y)
% This function creates returns the linear parameters of the
% slope (a) and y-intercept (b) given a set of input data (x,y).
% The function attempts to curve fit to linear, semilogy and log-log
% using natural logarithms.
% The returned values indicate those with the smallest sum of squared
% error.
% Calling parameters
%... (you fill in)
% Returned parameters
%... (you fill in)
% type flag indicating which type of equation had the best fit
% type=1 for linear, =2 for semilogy, =3 for log-log
 
Physics news on Phys.org
  • #2
% [c,d,type] = semilogy_ls2_xxx(x,y) % This function creates returns the linear parameters of the % slope (c) and y-intercept (d) given a set of input data (x,y). % The function attempts to curve fit to linear, semilogy and log-log % using natural logarithms. % The returned values indicate those with the smallest sum of squared % error. % Calling parameters %... (you fill in) % Returned parameters %... (you fill in) % type flag indicating which type of equation had the best fit % type=1 for linear, =2 for semilogy, =3 for log-log [e,f,type] = loglog_ls2_xxx(x,y) % This function creates returns the linear parameters of the % slope (e) and y-intercept (f) given a set of input data (x,y). % The function attempts to curve fit to linear, semilogy and log-log % using natural logarithms. % The returned values indicate those with the smallest sum of squared % error. % Calling parameters %... (you fill in) % Returned parameters %... (you fill in) % type flag indicating which type of equation had the best fit % type=1 for linear, =2 for semilogy, =3 for log-log % Initialize bestFit and typebestFit = Inf;type = 0;% Run all three fits and compare results[a,b,fitType] = linear_ls2_xxx(x,y);if a*b < bestFit bestFit = a*b; type = fitType;end[c,d,fitType] = semilogy_ls2_xxx(x,y);if c*d < bestFit bestFit = c*d; type = fitType;end[e
 

What is the purpose of comparing least square equations in Matlab?

The purpose of comparing least square equations in Matlab is to determine which equation fits a given set of data points the best. This is important in many scientific and mathematical applications, such as curve fitting and regression analysis.

How do I compare least square equations in Matlab?

To compare least square equations in Matlab, you first need to have the equations and the corresponding data points. Then, you can use the built-in functions such as "fit" and "polyfit" to calculate the coefficients of the equations. Finally, you can plot the equations and the data points to visually compare their fit.

What is the difference between linear and nonlinear least square equations?

The main difference between linear and nonlinear least square equations is the type of relationship between the independent and dependent variables. Linear equations have a linear relationship, meaning the dependent variable changes proportionally to the independent variable. Nonlinear equations have a more complex relationship, such as exponential or quadratic.

Can I compare more than two least square equations in Matlab?

Yes, you can compare multiple least square equations in Matlab by following the same steps as comparing two equations. You can plot all the equations and data points on the same graph to see their differences and similarities.

What factors should I consider when comparing least square equations in Matlab?

When comparing least square equations in Matlab, you should consider the goodness of fit (R-squared value), the number of data points, the complexity of the equation, and the purpose of the comparison. It is also essential to visually inspect the plotted equations and data points to ensure the best fit for your specific application.

Similar threads

  • Calculus and Beyond Homework Help
Replies
6
Views
641
  • Set Theory, Logic, Probability, Statistics
Replies
4
Views
1K
  • Set Theory, Logic, Probability, Statistics
Replies
6
Views
1K
  • Set Theory, Logic, Probability, Statistics
Replies
7
Views
473
  • Set Theory, Logic, Probability, Statistics
Replies
11
Views
748
  • Calculus and Beyond Homework Help
Replies
3
Views
2K
  • Calculus and Beyond Homework Help
Replies
12
Views
3K
  • Programming and Computer Science
Replies
4
Views
635
  • Advanced Physics Homework Help
Replies
0
Views
239
  • Set Theory, Logic, Probability, Statistics
Replies
3
Views
822
Back
Top