integration of FFT

I am supposed to calculate the fft of a rect function, and then getting the integration of answer. what I have done is :

fs = ceil(4*pi)+1;

xend = 3;

t = (0:1/fs:xend-1/fs)-1/3*xend;

x_f = zeros([1,fs*xend]);

x_f(1,(1/3*xend*fs):(2/3*xend*fs-1)) = 5.7737e19.*ones([1,(1/3*xend*fs)]);

m_f = length(x_f);

n = pow2(nextpow2(m_f))*4;

y = fft(x_f,n);

f = (0:n-1)*(fs/n);

power = y.* conj(y)/n;

y0 = fftshift(y); f0 = (-n/2:n/2-1)*(fs/n)/pi;

power0 = abs(y0);

plot(f0,power0);

K_fourier=power0;

K_int = int(K_fourier, -pi, pi);

then, I have this error: Undefined function 'int' for input arguments of type 'double'.

could anyone help me please?

Thank you

Answer 1

[Star Strider]

Use the trapz function.

Answer 2

[Thorsten]

The is no such function as int in Matlab. What is int supposed to do?

[Anita]

numerical integration.

Answer 3

[Shoaibur Rahman]

K_fourier is double type in your code. int cannot take double type as the function.

@ Thorsten: int performs all symbolic, definite, and indefinite integration of a function defined, and given as the input argument to int.

[Anita]

Thanks for your answer. Well, I'm aware about it and searching for a way to get the integration somehow. do you have any idea if it is possible to get integral of a 1x256 complex double or any other way to solve this problem?