Logic test returning unexpected answer

[pwarmuth]

2^(-x) == 1/(2^x) is returning 0. Any idea why?

[Helge Gabert]

Not surprising, because == doesn't do any and all simplifications for you.

Try (x-1)*(x+1) == x^2-1 also returns 0.

But x^2-1 == x^2-1 returns 1.

[pwarmuth]

Ok, that makes sense.

Speaking of simplifications, I encountered this today as well.
   

Those two statements should be mathematically identical, but yet their simplifications are not the same. I know for certain the second one is correct.

Though if I add in an explicit multiply, it behaves.
   

[Helge Gabert]

Yes, don't skimp on the '*'!

[Fortin]

Using the method, simplify(f-g)==0, works pretty well - where f ang g are the two items being compared.

For example: simplify(2^(-x) - 1/(2^x))==0

[Fortin]

(11-20-2015 05:31 PM)pwarmuth Wrote:  Ok, that makes sense.

Speaking of simplifications, I encountered this today as well.


Those two statements should be mathematically identical, but yet their simplifications are not the same. I know for certain the second one is correct.

Though if I add in an explicit multiply, it behaves.

This is because the intended implied multiplication involving 1/4 is calling 'of' instead of '*'.