"roots" function not working
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Hi,
I need to use the roots function to find the roots of a polynomial. I copied the text from the example @ the MathWorks.com entry for this function:
p = [1 -6 -72 -27];
r = roots(p);
However, r does not return, and the following error appears:
??? Subscript indices must either be real positive integers or logicals.
I cannot believe that Matlab cannot execute this simple code that is an official example. Does someone have any insight as to what the problem may be?
采纳的回答
Matt Fig
2011-3-1
You have a variable named roots. Do this :
clear roots
p = [1 -6 -72 -27];
r = roots(p);
Don't name variables after built-in MATLAB functions. (And especially don't blame MATLAB for your silly mistakes ;-))
3 个评论
Jan
2011-3-1
@Kyle: For checking: "which roots -all"
Kyle
2011-3-2
Anowarul Azim Evan
2021-3-18
rt=[1 1 1 1 1]; % all roots are 1 like (x-1)*(x-1)*(x-1)*(x-1)*(x-1)
p=poly(rt) % right-most is the constant value then x coefficient, then x^2 and so on...
roots(p)
%% roots
1.0008 + 0.0006i
1.0008 - 0.0006i
0.9997 + 0.0009i
0.9997 - 0.0009i
0.9990 + 0.0000i
%% Is it any bug? I was supposed to get 5 ones as roots.
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