How to vectorize an integral?

Question

Digvijay Rawat 2016-5-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/286235-how-to-vectorize-an-integral

评论： Star Strider 2016-5-28

function exdpo7_11        % script is function to allow for subfunctions
clc, close all;
clear
ans = 0;
n = -5:0.1:6;
int = integral(@fdpo7,-5,6);
disp(['integral = ',num2str(int)]);
fplot(@fdpo7,[-5 6]);
for i = 1:1:(length(n)-1)
    int = integral(@fdpo7,n(i),n(i+1));
    ans = ans+int;       
end
ans
function y = fdpo7(x)
if x < -1
    y = exp(x+1);
elseif x < 5
    y = 2 + cos(pi*x);
else 
    y = 2*(x-5) + 1;
end

Hi!

In the above piece of code, I have to calculate the integral of the function given in the subfunction 'fdpo7' using vectorization. I have already calculated the integral using a for loop as you can see but I am unable to think as to how to integrate the function by vectorising the code and not using the for loop. Any help will be appreciated.

Thanks!

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Answer 1

Star Strider 2016-5-28

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/286235-how-to-vectorize-an-integral#answer_223725

编辑：Star Strider 2016-5-28

在 MATLAB Online 中打开

This will likely work:

fdpo7 = @(x) exp(x+1).*(x < -1) + (2 + cos(pi*x)).*((x < 5) & (x >= -1)) + (2*(x-5) + 1).*(x >= 5);
x = linspace(-10, 10);                  % Test & Plot
figure(1)
plot(x, fdpo7(x))
grid

The ‘Test & Plot’ section is not necessary for the code. I just shows that the ‘y’ function does what you want it to.

EDIT — I originally named the function ‘y’, corrected it to be ‘fdpo7’.

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Digvijay Rawat 2016-5-28

Worked! Thanks a lot for your help :)

PS : The edit was not necessary, I am not that new to MATLAB :P

Star Strider 2016-5-28

My pleasure!

Your code appears to be sophisticated, but I wanted to remove any ambiguity. It’s always best to provide seamless code, as you will discover when you join the happy throng here providing Answers, and start guiding others. Please share your expertise here when you have the time.

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