How to integrate using a for loop and plot the result?

Question

Andrea Sartori 2018-1-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/375612-how-to-integrate-using-a-for-loop-and-plot-the-result

评论： Géry van der Rest 2019-5-5

Hi, I need to integrate a function using LOOP FOR and plot the result. For example f(x)= cos(x) with 0<=x<=pi. Practically I want to divide the area under the curve in a lot of trapezes, calculate their area and sum them. Can you help me? thank you!!

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Chris Perkins 2018-1-8

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/375612-how-to-integrate-using-a-for-loop-and-plot-the-result#answer_299207

编辑：Chris Perkins 2018-1-8

在 MATLAB Online 中打开

Hi Andrea,

You can use "linspace" to create a large number of points over your given range, then calculate the function value at each iteration of the loop, and then calculate the area using the function value and the size of the step. You could plot the area at each step of the loop, or any other values, depending on what exactly you want to plot.

Here's a quick example, using cos(x):

totalArea = 0;
x = linspace(0,pi,10000);
f = zeros(1,length(x));
stepSize = x(2) - x(1);
for i = 1:length(x)
    f(i) = cos(x(i));
    totalArea = totalArea + f(i) * stepSize;
end
disp(totalArea);

Alternatively, if you only need to find the integral, you can use the function "integral", as described on the following documentation page:

https://www.mathworks.com/help/matlab/ref/integral.html

2 个评论
显示无隐藏无

Andrea Sartori 2018-1-8

Thank you Chris! You've been vey helpful

Géry van der Rest 2019-5-5

Hi,

Is is possible to do the same procedure, but if the function that I want to integrate is the product of several functions? for example, I want to integrate the function h(x)=(3x^2+x)*(e^3x) by doing a for loop. Can I use the same strategy as the one explained here ?

Thank you very much.

请先登录，再进行评论。