Why does the distributive property fail when comparing expressions?

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As a simplified example, I'm trying to compare whether two expressions are equal, where they are simply written differently. But
syms a x y;
logical((x+y)*a == x*a + y*a)
returns false, and everything else that assumes distributivity of + and *. Is there some other function that will help me, or some explanation why this happens?

Answers (1)

Star Strider
Star Strider on 18 Apr 2018

To get logical results with symbolic expressions, use the isAlways (link) function.

syms a x y;
TF = isAlways((x+y)*a == x*a + y*a)
TF =
    logical
     1

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