subscript indices must either be real positive integers or logicals when using a function in a nested for?

I use this function in a nested for and I get this error: subscript indices must either be real positive integers or logicals

Zpred = h(Xpred)

where Xpred is a matrix

function zk=h(x)
zk(1,:)=sqrt(900+(x(1,:)-30).^2);
zk(2,:)=x(2,:).*(x(1,:)-30)./zk(1,:)

can anyone help me to find the error

[Joseph Cheng]

function zk=h(x) 
   zk(1,:)=sqrt(900+(x(1,:)-30).^2); 
   zk(2,:)=x(2,:).*(x(1,:)-30)./zk(1,:)

Answer 1

[Image Analyst]

I think the FAQ explains it really well: http://matlab.wikia.com/wiki/FAQ#How_do_I_fix_the_error_.22Subscript_indices_must_either_be_real_positive_integers_or_logicals..22.3F

When you're calling this:

Zpred = h(Xpred)

at that point, it thinks h is an array, not a function like you thought.

Your script/function is not called h.m is it? Or else somethere else earlier in your code, you must have used h in a way that created an array called h.

[sH]

Thanks everybody

Answer 2

[Joseph Cheng]

so when i run the code you have:

 function zk=h(x) 
   zk(1,:)=sqrt(900+(x(1,:)-30).^2); 
   zk(2,:)=x(2,:).*(x(1,:)-30)./zk(1,:);

with the input

 h(randi(10,2,1))

i don't get the error. Now with this type of error the fastest thing is for you to use the debugger and solve it. Put a breakpoint at the call, verify the input Xpred is actually what you want, there is no variable or other item already called h, and if everything checks out step inside the function where is the line that the error says it is?

[sH]

I have already called h for another variable HOw should I use debugger please explain more

[Joseph Cheng]

you should not use 'h' to describe a function and a variable. Matlab is not smart enough to understand which one you're trying to use.

Here is an example: if my dog is called Brian and I have a friend called Brian, and I ask you to take Brian outside. You wouldn't not know which one to take out side would you? Call your function another name or use another variable name for h.

*sorry to anyone named Brian. It was the first name i could think of.

[sH]

no I meant that I'm calling function h for the second time. when I use it separately, I don't get any error but when I use it in a nested for in a larger simulation I get this error