Error with a function

Question

Corey Bullard 2012-4-25

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/36524-error-with-a-function

I have three errors:

??? Subscript indices must either be real positive integers or logicals.
Error in ==> velocity at 3
v = -r*angular_velocity(sin(angular_velocity*t)+((r)/(2*l_value))...
Error in ==> HW10 at 19
    x_dot = velocity( r, angular_velocity, t, l_value );

This is part of my script:

for l_value = (r + .5):((15-(r + .5))/5):15;
    x_dot = velocity( r, angular_velocity, t, l_value );
    v(m) = x_dot;
    m = m + 1;
    plot(x_dot,l_value);
end

The error seems to be with the function. Here is the function velocity:

function [ v ] = velocity( r, angular_velocity, t, l_value )
%Calculate velocity
v = -r*angular_velocity(sin(angular_velocity*t)+((r)/(2*l_value))...
    *((sin(2*angular_velocity*t))/(sqrt(1-((r/l_value)*(...
    sin(angular_velocity*t)))^2))));
end

Any help or tips will be greatly appreciated!

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Answer 1

Walter Roberson 2012-4-25

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/36524-error-with-a-function#answer_45667

angular_velocity*t implies that angular_velocity is a numeric quantity (scalar, vector, array). sin() of that would also be a numeric quantity, but very likely not positive-integer-valued. You then use angular_velocity indexed at that sin() expression, so that is likely to fail.