Warning: Infinite or Not-a-Number value encountered.

Dear all,

I am facing the warning (Infinite or Not-a-Number value encountered.) in my following code. Due to the Nan/Inf values, the output of my complete code is erratic. Please help me solve the issue, thanks. Body of affected portion of code is as under:

clear all
clc
AB=0.34;
j=1;
x(1)=(15*AB);
z(1)=0;
while z <= 0.3
    j=j+1;
    z(j)=z(j-1)+0.020;
    i=1;                    
            
while  x(i)<=(15*AB) && x(i)>=(-15*AB)
        i=i+1;
        x(i)=x(i-1)-(AB/10);
        
        f1=@(l)exp(-(x(i)/1000-l.*cos(0.2663)).*(1.67./ (2.*4.18e-6))).*(besselk(0,((1.67./(2.*4.18e-6)).*sqrt((x(i)/1000-l.*cos(0.2663)).^2+(z(j)/1000+l.* sin(0.2663)).^2))));
        % Lower limit of integral
        a=0.000001;
        % Upper limit of integral
        b=AB/1000;
        integral1(i)=integral(f1,a,b);
end
end

[Mathieu NOE]

hello

I noticed the f1 function values are always zero

test the following part : (besselk(0,((1.67./(2.*4.18e-6)).*sqrt((x(i)/1000-l.*cos(0.2663)).^2+(z(j)/1000+l.* sin(0.2663)).^2))));

this is always zero at each loop iteration;

[Waseem Akhtar]

@Mathieu NOE Thank you for your comment.

I checked the part you mentioned which is a Modified Bessel function but the formulation or values seem to be ok.

I also tried to split the function in two parts as follows:

''

f1=@(l)exp(-(x(i)/1000-l.*cos(0.2663)).*(1.67./ (2.*4.18e-6)));

f2=@(l)(besselk(0,((1.67./(2.*4.18e-6)).*sqrt((x(i)/1000-l.*cos(0.2663)).^2+(z(j)/1000+l.* sin(0.2663)).^2))));

% Lower limit of integral

a=0.000001;

% Upper limit of integral

b=AB/1000;

integral1(i)=integral(f1,a,b);

integral2(i)=integral(f2,a,b);

value(i)=integral1(i).*integral2(i);

''

I noticed that the first part (f1) has infinite values after certain iterations whereas 2nd part (f2) has finite or zero values. I am not sure if some other integration technique could help. I have also tried "quad fn" and "Simpson's rule" but to no use. I am not sure how to solve this issue :(

[Mathieu NOE]

ok so the problem is find why f1 has infinite values - at which iteration does it appear ?