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+--- Thread: Equation validator (==) problem (/thread-14945.html)
Equation validator (==) problem - superludvig - 05-08-2020 12:34 PM
So I have this inconvenience when using my calculator to check if what I think is the same thing actually is the same thing. This is really handy when comparing equations while shortening them.
So here is the problem:
I input 2*2==4 and I get a 1, which means it's true.
And then I input 9^(1/2)==3 and I still get a 1.
The problem occurs when I input 9^(1/2)==(-3) because then I get a 0.
Why do I get a 0 and is there any way to have the calculator display a 1 instead?
RE: Equation validator (==) problem - Albert Chan - 05-08-2020 12:55 PM
(05-08-2020 12:34 PM)superludvig Wrote: Why do I get a 0 and is there any way to have the calculator display a 1 instead?
If calculator return 1 for both 9^(1/2)==3 and 9^(1/2)==-3, by transitive propoerty, 3==-3
You can move the exponent to the other side, 9 == 3^2 == (-3)^2
RE: Equation validator (==) problem - DrD - 05-08-2020 02:29 PM
(05-08-2020 12:55 PM)Albert Chan Wrote: You can move the exponent to the other side, 9 == 3^2 == (-3)^2
Did you try that in both [HOME] and [CAS]?
[HOME]
9 == 3^2 == (-3)^2; ==> 0
[CAS]
9 == 3^2 == (-3)^2; ==> true
RE: Equation validator (==) problem - Albert Chan - 05-08-2020 03:42 PM
Hi, DrD
XCas (1.5.0-63 win32) support chained comparison , but not fully short circuiting.
XCas> f(x) := {print(x);x}
XCas> f(1) < f(2) < f(3) < f(-1) < f(-2) < f(-3)
x:1
x:2
x:2
x:3
x:-1
x:-3
→ false
Python 2.6:
>>> def f(x): print x; return x
...
>>> f(1) < f(2) < f(3) < f(-1) < f(-2) < f(-3)
1
2
3
-1
False