How to integrate a symbolic function?
2 views (last 30 days)
Show older comments
Hello,
I´m trying to integrate a symolic expression. Therefore I use the MATLAB command "int". But the problem is that it seems like Matlab doesn´t calculate that integral. If I try to convert the result into a numeric number: double(result) then I will get an error.
Could somebody help me, please?
This is my code:
tfail = [5571.760,5573.742,5654.457]
n = length(tfail)
beta_hat = 4.2915822
B_hat = 1861.6186657
C_hat = 58.9848692
syms t B beta C
y(t) = (exp(-B_hat/((heaviside(t)-heaviside(t-2000))*(330)+(heaviside(t-2000)-heaviside(t-3000))*(350)+...
(heaviside(t-3000)-heaviside(t-14000))*(390))))/C_hat;
logL=0;
for i=1:n
tfail(i)
I(i) = int(y(t),t,0,tfail(i))
y_new(i)=subs(y,t,tfail(i))
logL =logL+log((beta*y_new(i)*(I(i))^(beta-1))*exp(-((I(i))^beta)))
end
PS: for i=1, I should get for the integral I(t=5571.76)=0.57185
0 Comments
Accepted Answer
Walter Roberson
on 23 Jan 2016
You have subs(y,t,tfail(i)) when y is a function. You invoke functions on values, not subs() the values.
y_new(i) = y(tfail(i))
More Answers (0)
See Also
Categories
Find more on Symbolic Math Toolbox in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!