Automatic Equation and Inequation evaluation.

[Carlos]

On Saturday, 15 June 2013 at 14:42:38 UTC, monarch_dodra wrote:
> On Saturday, 15 June 2013 at 13:23:07 UTC, Carlos wrote:
>> On Saturday, 15 June 2013 at 12:36:26 UTC, monarch_dodra wrote:
>>> On Saturday, 15 June 2013 at 11:44:03 UTC, Carlos wrote:
>>>> On Saturday, 15 June 2013 at 08:46:13 UTC, John Colvin wrote:
>>>>> On Saturday, 15 June 2013 at 02:05:00 UTC, Carlos wrote:
>>>>>> I'm interested in this kind of functionalities; Does D have
>>>>>> something on this ?
>>>>>>
>>>>>> I thought about something like a "eval" function that 
>>>>>> would use
>>>>>> specified algorithms.
>>>>>> something likes this
>>>>>>
>>>>>> import std.stdio, std.math, std.eval;
>>>>>>
>>>>>> void main()
>>>>>> {
>>>>>> eval(Real; a+b^^x+c=56){
>>>>>> algor.brute(&result);
>>>>>>   }
>>>>>> writeln("Positive value is : ", result);
>>>>>> }
>>>>>
>>>>> It's not clear what that would do from your example. I 
>>>>> presume a, b and c are defined somewhere and eval solves 
>>>>> for x?
>>>>
>>>> algor.brute does the work. IF you know that algorithm you 
>>>> would know what it does.
>>>> Another question would be if this way of coding makes sense 
>>>> to you.
>>>>
>>>> This is what the "eval" function does ( in theory ), It 
>>>> takes The words : Real, Rational, Irrational or R, Q , Q' 
>>>> and from there is defined which numerical group is going to 
>>>> be used for the evaluation. Then it identifies the operators 
>>>> and variables and defines the equation in a format like a 
>>>> text format with a end file character in the end so 
>>>> equations can be as long as you want. After that between 
>>>> {algor.(name)} in name you call the algorithm you want to 
>>>> use for the evaluation there can be predefined algorithm 
>>>> with D but maybe you can define your own algorithms.
>>>>
>>>> What do you think does this makes sense or would you 
>>>> implement it other way ?
>>>
>>> D provides no such thing. AFAIK, there is nothing in Phobos 
>>> provided that does it either.
>>>
>>> It should be doable, where the second argument is a string. 
>>> Something like:
>>> auto eq = Equation(Real, "a+b^^x+c=56");
>>> auto result = Equation.brute();
>>>
>>> I think it would quite a specialized numerical library 
>>> though, so I don't think it would find its way into the 
>>> standard library.
>>>
>>> I'm not sure any such D Library exists. You'll either have to 
>>> port an existing library, or link with a C/C++ existing 
>>> library.
>>
>> OK but if developed it would be included in D ? Right ? It 
>> would be very useful I think.
>
> Depends what you mean by "included in D" ? In the standard 
> library, I wouldn't know (but I don't think so). But that 
> doesn't mean it couldn't be distributed as a trusted and 
> reliable third party library.

I mean that anyone with the code can use it without installing 
anything but the compiler package. And third party could be the 
first choice before it could be included.