There seems to be some sort of inconsistency when using symbols vs literals
-
>>> ITE(True, 3, 4)
True
>>> a, b, c = symbols('a b c')
>>> ITE(a, b, c).subs([(a, True), (b, 3), (c, 4)])
3
On Friday, April 4, 2014 11:33:56 PM UTC-4, SAHIL SHEKHAWAT wrote:
>
> It is not necessary for all the arguments of ITE to be bool. If x,y and z
> are all arbitrary variables (but not numbers) this is what it gives.
> * >>> ITE(x,y,z)*
> * Or(And(Not(x), z), And(x, y))*
> And you are getting this error because of the above logical statement *(*you
> can not add two logical statements but if by "+" you mean "Or" please use "
> | "*)* But if instead of that like, i said earlier, if "Cond" in your
> example is either* True *or *False* your statement will return* ( x + y )*
> * >>> ITE(True,x,y) + ITE(True,y,x)*
> * x + y*
>
> And about x and y being a number, ITE does not support that . It takes
> them as being bool.
> The reason the arbitary variables work but number don't is that ITE is a
> logical boolean function which converts number into bools whereas you can
> use variables because they can be specified to be bools like
> * >>>x = symbols(x,is_Boolean=True)*
>
> *I am not sure if we want numbers to be included in ITE or they are just
> fine. it will be nice if other developers also comment.*
> *Thanks*
>
> On Friday, April 4, 2014 9:55:58 PM UTC+5:30, Mehul Tikekar wrote:
>>
>> I am referring to the ITE function defined in sympy here:
>> http://docs.sympy.org/dev/_modules/sympy/logic/boolalg.html#ITE. But it
>> requires all three arguments to be boolean. When I try:
>>
>> cond, x, y = symbols('cond x y')
>> ITE(cond, x, y) + ITE(cond, y, x)
>>
>> I get a TypeError: unsupported operand type(s) for +: 'Or' and 'Or'
>>
>> On Friday, April 4, 2014 12:17:00 PM UTC-4, SAHIL SHEKHAWAT wrote:
>>>
>>> I don't understand what you mean by boolean ITE function can you please
>>> explain that?
>>> BUT I think ITE work well if "cond" is a bool when "x" and "y" are
>>> arbitary symbols. for example:
>>> IN [1]:* ITE**(True, x , y)*
>>> OUT [1]:* x*
>>>
>>> in the second part of your question if "cond" is a bool then yes ,*
>>> ITE'(cond, a, b) + ITE'(cond, b, a) *will return* (a+b)*
>>>
>>>
>>> On Fri, Apr 4, 2014 at 9:23 PM, Mehul Tikekar <[email protected]>wrote:
>>>
>>>> Hi,
>>>> I am looking for a variant of the boolean ITE(cond, x, y) function.
>>>> I need only "cond" to be a bool while "x" and "y" are arbitrary symbols
>>>> (they could be numbers, for example). Does sympy have a function like
>>>> that?
>>>> If not, any ideas on how I can go about writing one? Ideally, it should
>>>> also be able to do simplifications. For example, ITE'(cond, a, b) +
>>>> ITE'(cond, b, a) should be simplified to (a + b).
>>>>
>>>> Mehul
>>>>
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>>>
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