Error using sym/subsref
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Rohit Tamrakar
on 4 May 2020
Commented: Rohit Tamrakar
on 4 May 2020
I have this program to get the value of "m"
clc
syms m
eqns = (72*m^2)-(1.5*m^3) == 358;
S=solve (eqns,m,'Real',true)
double (S.m);
However in the output I get this error
S =
32*cos(atan(2167511^(1/2)/5965)/3) + 16
16*3^(1/2)*sin(atan(2167511^(1/2)/5965)/3) - 16*cos(atan(2167511^(1/2)/5965)/3) + 16
16 - 16*3^(1/2)*sin(atan(2167511^(1/2)/5965)/3) - 16*cos(atan(2167511^(1/2)/5965)/3)
Error using sym/subsref
Too many output arguments.
Error in Untitled (line 5)
double (S.m);
Can any body help me with this?
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Accepted Answer
Walter Roberson
on 4 May 2020
When there is only a single variable being solved for, and ReturnConditions is not set, then solve() does not return a structure containing the one variable: it returns the value of the variable. In terms of your code, that means you would use
double(S) %instead of double(S.m)
Or you could instead
S=solve (eqns, m, 'Real', true, 'returnconditions', true);
and then S.m would exist.
3 Comments
More Answers (1)
Mathias Andersen
on 4 May 2020
Double(S) will produce a matrix with the solutions.
S.m is not a variable stated anywhere in the script
4 Comments
Walter Roberson
on 4 May 2020
Not when you solve for a single variable and you do not have ReturnConditions true: in that case, MATLAB cannot tell that apart from the case where you want the non-struct version of the solution.
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