Output of propositional functions
01-12-2017, 05:40 AM
Post: #1
 Alberto Candel Member Posts: 169 Joined: Dec 2013
Output of propositional functions
A propositional function outputs 0/1 or True/False depending on ...? Maybe someone knows how to always get True/False. I explain:

The function gt0(x):=x>0 outputs 0/1: for example gt0(2)=1 and gt0(-1)=0. But the function ge0(x):=x &ge; 0 outputs True/False (&ge; is the html code for "at least"), for example ge0(2)=True and ge0(-3)=False.

Is there some kind of switch that will always give True/False as possible answers?

BTW, Xcas seems to always return True/False
01-13-2017, 12:06 PM
Post: #2
 roadrunner Senior Member Posts: 429 Joined: Jun 2015
RE: Output of propositional functions
I don't know of a switch, but this function returns true and false in CAS:

g2(x):=BEGIN IF x>0 THEN RETURN(true); END ; RETURN(false); END;

In HOME I think you will always get 0 or 1.

01-13-2017, 05:00 PM
Post: #3
 DrD Senior Member Posts: 1,133 Joined: Feb 2014
RE: Output of propositional functions
If you can tolerate string objects, you could return "True" and "False" in Roads program.
01-14-2017, 04:44 AM
Post: #4
 Alberto Candel Member Posts: 169 Joined: Dec 2013
RE: Output of propositional functions
Thank you. I was looking for something already there, avoiding programming. For my students.
01-14-2017, 12:49 PM
Post: #5
 compsystems Senior Member Posts: 1,342 Joined: Dec 2013
RE: Output of propositional functions
(01-13-2017 12:06 PM)roadrunner Wrote:  I don't know of a switch, but this function returns true and false in CAS:

g2(x):=BEGIN IF x>0 THEN RETURN(true); END ; RETURN(false); END;

In HOME I think you will always get 0 or 1.

I agree, in HOME should return 1/0 but in CAS MODE always TRUE / FALSE as constants without evaluating.

CASs must show SYMBOLIC and non-numerical values

return PI -> π and not 3.14....
return true -> true and not 1
return false -> false and not 0

To see the numerical value, there are the EVAL commands,

EVAL(TRUE) -> 1
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