"Subscript indices must either be real positive integers or logicals"

Question

Anke Kügler 2015-10-31

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/252022-subscript-indices-must-either-be-real-positive-integers-or-logicals

评论： Star Strider 2015-11-1

采纳的回答： Star Strider

在 MATLAB Online 中打开

Hi,

I'm not sure if this is the right title, but I ran into a problem with my current code.

speed=[1511 1505.7 1490.2 1484.1 1480.3 1481.8 1485.4 1491 1506.3 1524 1548.6];
depth=[0 85 165 295 665 1005 1505 2005 3005 4005 5000];
phi=20;
i=1;
r=0;
while r<4000
n=1;
xn=1;    
for i=1:11
      c1=speed(1,i);
      z1=depth(1,i);
      z2=depth(1,i+1);
      c2=speed(1,i+1);
      a=sind(phi)/c1;
      for z=z1:z2  
            m=(c2-c1)/(z2-z1);    
            n=c1-m*z1;    
            cn=m*z+n;
            theta=asind(a*cn);
            dx=(z-(z+1))*tand(theta);
            xn=xn+dx
            x(1,n)=abs(xn);
            y(1,n)=z;
            n=n+1
            r=abs(xn);  
      end
  end
  phi=phi+5; 
end

However, if I run it, I get the error

Subscript indices must either be real positive integers or logicals.
Error in ATOC (line 83)
x(1,n)=abs(xn);

which I don't understand, because n should be a positive integer...

Any ideas? Thank you very much!

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Answer 1

Star Strider 2015-10-31

0
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https://ww2.mathworks.cn/matlabcentral/answers/252022-subscript-indices-must-either-be-real-positive-integers-or-logicals#answer_198037

在 MATLAB Online 中打开

You have two definitions of ‘n’ in your loop, first:

n=c1-m*z1;

then later:

n=n+1;

The first one is creating fractional values for ‘n’, and that is what is throwing the error. It occurs when the lengths of ‘x’ and ‘y’ each have 1511 elements. Since I do not know what you are doing, I cannot offer any specific solution.