Converting symbolic boolean to MATLAB boolean

2011 5 27
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Hi,
I have a symbolic expression that can be evaluated to true / false, and I would like to get that result back to MATLAB.
This is what I have tried:
>> sym('1>0')
ans =
0 < 1
>> simplify(sym('1>0'))
ans =
TRUE
>> double(simplify(sym('1>0')))
??? Error using ==> eval
Undefined function or variable 'TRUE'.
Error in ==> sym.sym>sym.double at 937
X = eval(Xstr);
>> logical(simplify(sym('1>0')))
??? Error using ==> logical
Conversion to logical from sym is not possible.
>>
Thanks Joan

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Oleg Komarov
Oleg Komarov 2011-5-27
Is the simplify avoidable?
Joan Puig
Joan Puig 2011-5-27
The reason why I use the simplify is so that I end up getting a TRUE/FALSE

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Walter Roberson
Walter Roberson 2011-5-27

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strcmp(char(sym('TRUE')),'TRUE')

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Joan Puig
Joan Puig 2011-5-27
This would work, but I was hoping to get a "native" way to do the conversion
Walter Roberson
Walter Roberson 2011-5-27
piecewise() or _if() might be easiest. Neither of those appear to have MATLAB interfaces, though, so you might need to use evalin().
Joan Puig
Joan Puig 2011-5-27
Actually, the _if trick will do, and also, it solves another problem I had
Thanks!

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