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How to use isAlways to compare two symbolic equations ?

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CN.
CN. 2021-5-31
评论： Torsten 2021-5-31
Dear forum members,
I would like to check wether or not two symbolic equations are the same, but I am not able to do this using isAlways function.
syms a b
f1 = y == abs(x);
f2 = y == sqrt(x^2);
isAlways(f1 == f2)
Warning: Unable to prove '(y == abs(x)) == (y == (x^2)^(1/2))'.
> In symengine
In sym/isAlways (line 42)
ans =
logical
0
Why do I get these warnings and this (false) answer "logical 0" ? What am I doing wrong ?
Thank you for your help.

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回答（1 个）

Torsten
Torsten 2021-5-31
syms x
isAlways(sqrt(x^2)==abs(x))
  2 个评论
CN.
CN. 2021-5-31
Thanks for your answer, but I already tested this solution and got the same result :
isAlways(sqrt(x^2)==abs(x))
Warning: Unable to prove '(x^2)^(1/2) == abs(x)'.
> In symengine
In sym/isAlways (line 42)
ans =
logical
0
Torsten
Torsten 2021-5-31
Ok. Then the symbolic toolbox is not able to proove the identity.

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