MATLAB: Definite Integrals in for-loop

integration

I'm trying to setup up this loop. But before I do that I need to declare the functions:
n_grid   =    20;  %  Size  of    rid
Ms       =    [];
Js       =    [];
Ns       =    [];
Es       =    [];
J        =    linspace(0,1,1000);
kappa = 2.*sinh(2*J)./(cosh(2*J)).^2;
kappam = 2*(tanh(2*J)).^2-1;
z = exp(-2*J);
K1 = int(sqrt(1- kappam.^2 * sin(phi).^2), phi= 0.. pi/2)
% Calculating Energy & Magnetisation as a function of interaction strength
E = -J.*(coth(2*J)).*(1+(2/pi)*kappam.*K1(kappam));
An error for K1 shows as follows:
Undefined function 'K1' for input arguments of type 'char'.
Error in ising (line 12)
K1 := int(sqrt(1- kappam.^2 * sin(phi).^2), phi= 0.. pi/2)
What's wrong with my syntax?

Best Answer

Please try code below
J = linspace(0,1,1000);
kappam = 2*(tanh(2*J)).^2-1;
f = @(phi)sqrt(1- kappam.^2 * sin(phi).^2);
K1 = integral(f,0,pi/2,'ArrayValued',true);
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