Subscript indices must either be real positive integers or logicals.

function T=baryeval2(tau,s,c,belta,x)

u=zeros(size(x))
d=zeros(size(x))
T=zeros(size(x))

for k=1:5
    u=u+s(k).*belta(k).*(x-tau(k)).^(-1);
    d=d+c(k).*belta(k).*(x-tau(k)).^(-1);
end
T=u./d;
end

[Azzi Abdelmalek]

You can copy and paste your code instead of inserting an image.

Answer 1

[Azzi Abdelmalek]

You cant use an index equal to zero, Matlab allows only positive integer indices, or logical indices

[Yintong Zheng]

do you mean I should change k=1:4?I tried to chang like this, but it still appears the same error. What else might need to be change?

[Walter Roberson]

Is it possible that you defined "sin" or "cos" as a variable?

I notice that the error message does not correspond to the code you posted. Please post your current code and corresponding error message.

[Yintong Zheng]

I changed my code and now I get answers. But apparently something is wrong! Please help me to fix it.

[Yintong Zheng]

I insert all the values of tau, s, c, belta at command window. And all those '-Inf' are what I got.

Answer 2

[the cyclist]

MATLAB has 1-based indexing. When you enter

tau(k)

for k = 0, there is no such element.

[Yintong Zheng]

should I delete '(k)'this part?

Answer 3

[Walter Roberson]

You have, in part, (x-tau(k)).^(-1) . If there is any x equal to tau(k) then the subtraction would give 0 and raising that to power -1 would give infinity. Infinity times any non-zero value gives infinity (infinity times 0 gives nan), so you would be adding infinity to the value, resulting in infinity. And then since you are effectively totaling values, you are going to get an infinite result.

[Yintong Zheng]

can you advice me how to fix this?

[Walter Roberson]

If you do have an x equal to some tau, then inf or nan is the correct answer for the formulae you have written. The situation is exactly like asking to total 1/x when x is allowed to be 0.

Answer 4

[Image Analyst]

THE FAQ explains it pretty 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