Plot error bars in curve fitting figure

Hi I would like to know how to add error bars to the figure of the curve fitter.

Answer 1

[Star Strider]

Using fitnlm since I am familiar with it —

x = 0:20;
y = 1-exp(-0.25*x) + randn(size(x))*0.1;

objfcn = @(b,x) b(1) - exp(b(2).*x) + b(3);

mdl = fitnlm(x(:),y(:), objfcn, rand(3,1))

Warning: The Jacobian at the solution is ill-conditioned, and some model parameters may not be estimated well (they are not identifiable). Use caution in making predictions.

mdl = 
Nonlinear regression model:
    y ~ b1 - exp(b2*x) + b3

Estimated Coefficients:
          Estimate       SE        tStat       pValue  
          ________    ________    _______    __________

    b1      434.96    0.015592      27897    8.6967e-74
    b2    -0.25979    0.037878    -6.8586    1.5222e-06
    b3     -433.96    0.015592     -27833    9.0871e-74


Number of observations: 21, Error degrees of freedom: 19
Root Mean Squared Error: 0.0806
R-Squared: 0.92,  Adjusted R-Squared 0.916
F-statistic vs. constant model: 219, p-value = 6.94e-12

[yf,yci] = predict(mdl, x(:));

figure
plot(x, y, '.:')
hold on
errorbar(x, yf, yci(:,1)-yf, yci(:,2)-yf)
hold off
grid
xlim([-1 21])

A similar approach would likely work with the Curve Fitting Toolbox functions.

It will be necessary for you to experiment with those in your project.

.