how can i do Trapezoidal rule? - error

clc
clear
format long


d = [0.05 0.025 0.0125 0.00625 0.003125];
syms x y
f= 10000.*exp(y)/(1+abs(x)./2) ;

I_t_x = int(f,x,-5,0);
I_t = double(int(I_t_x,y,-2,2))

for i = 1:length(d)
    x = -5 : d(i) : 0 ;
    y = -2 : d(i) : 2 ;
    
    [X,Y] = meshgrid(x,y);
    F = 10000*exp(y)/(1+abs(x)/2) ;
    I = trapz(y,trapz(x,F,2))

    

end

[Jan]

Please post code as text, because then it can be reused easily to write an answer.

Whenever you mention an error in the forum, post a complete copy of the message. Then the readers can concentrate on solving the problem, instead on investing time in guessing, what the error is. You do have this important information on the screen already, so sharing it is the way to go.

[jeaho jang]

I fixed it.

Answer 1

[Jan]

Which error message do you get?

This should fail, if x and y are symbolic variables:

    [X,Y] = meshgrid(x,y);

And you do not use the output X and Y at all:

    F = 10000*exp(y)/(1+abs(x)/2) ;
    I = trapz(y,trapz(x,F,2))

[jeaho jang]

I want to solve this function with trapezoid rule.

-5 <= x <= 0

-2 <=y <= 2

how can i do?

del x and del y = 0.05 0.025 0.0125 0.00625 0.003125

[Torsten]

In your code, use

F = 10000*exp(Y)./(1+abs(X)/2)

And save the integration results in a vector:

I(i) = trapz(y,trapz(x,F,2))

[jeaho jang]

This modification will also result in an error.

clc
clear
format long


d = [0.05 0.025 0.0125 0.00625 0.003125];
syms x y
f= 10000.*exp(y)/(1+abs(x)./2) ;

I_t_x = int(f,x,-5,0);
I_t = double(int(I_t_x,y,-2,2))

for i = 1:length(d)
    x = -5 : d(i) : 0 ;
    y = -2 : d(i) : 2 ;
    
    [X,Y] = meshgrid(x,y);
    F = 10000*exp(Y)/(1+abs(X)/2);
    I(i) = trapz(y,trapz(x,F,2))

    

end

[Torsten]

In the definition of F, I wrote ./, not only /

[jeaho jang]

Thank you torsten