# how can i fix this error "Array indices must be positive integers or logical values"?

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ELISABETTA BILLOTTA on 21 Oct 2021
Edited: Cris LaPierre on 22 Oct 2021
knowing that z2 is a function that determines the angles, vq2 are velocities determined with interpolation, d are reference angles and vel_thr are fixed speeds in the following for loop this error is thrown " Array indices must be positive integers or logical values".
x = [0 157 670 1255]; %distance
v = [0 7 30 70]; %velocity
xq = z1; %distance
vq2 = interp1(x,v,xq,'linear');
d= [-161.42 -125.58 -89.74 -53.91 -18.07 17.76 53.59 89.43 125.27 161.11];
vel_thr= [5 6 15 25 30 35 45 55 60 70];
for i=1:length(z2);
angsel=z2(i)*180/pi;
[tmp1 icol1]=min(abs(angsel-d));
[tmp2 icol2]=min(abs(360+angsel-d));
if tmp1<tmp2
icol(i)=icol1;
else
icol(i)=icol2;
end
velsel=vq2(i);
itmp=find(velsel>=vel_thr);
irow(i)=itmp(end);
prob(i)=CF20(10+irow(i),1+icol(i));
end
CF20 is a 20x11 matrix of numbers all greater than or equal to zero. i tried to insert these values both with an excel file and with a txt file, but in both cases it doesn't work.
how can I solve this problem?

Cris LaPierre on 22 Oct 2021
Edited: Cris LaPierre on 22 Oct 2021
The error means that you are either using a number less that 1, or a decimal number to index a variable. As the error says, your index values must be positive integers or logicals.
With your code, I suspect icol(i) is not always an integer.
angsel=z2(i)*180/pi;
[tmp1 icol1]=min(abs(angsel-d));
Below is a simple example to explain the error
A = 1:5;
% Works
A(1)
ans = 1
% Doesn't work
A(1.5)
Array indices must be positive integers or logical values.