#17 Allow equations with operators other than "="

[zeon_account_will_be_deleted]

Hi, Jan.

I had noticed [r127] some time ago.

Does this mean an inequality support?

What I see now. I can create an inequality:
EQDEF @1@ a < b
But the "VAL(a)" formula returns "a = b" now(!)
"REV(@1@)" returns "b < a" too. Expected to see "b > a" (Yes, exactly ">", because "b < a" is a brand new equation)

[Jan Rheinlaender]

Hi zeon,

that's not a feature request, its a bug report :-)

Thanks for reporting them. I think they are fixed now.

Jan

[zeon_account_will_be_deleted]

Well, Okay :)

Will iMath really understand, that a is less than b? Then VAL(a) shoould return the expression "a⊂(-∞:b)"
Will iMath support these types of inequalities:
"a ≠ d"
"c ≤ a < b"
"a⊂[c:b)"?

...and all things that could be done with them:
- Multiplying both sides of inequality. "<" or "≤" symbols must be sensitive to negative values of multiplier;
- Exponentiation: the same;
- If "a>1" than, e.g. "c=ln(a)" should never be less or equal "0" or have a complex value. It should be taken into consideration while solving other equations (c assumed to be a real positive value)

My feature request is to provide more support for inequalities as far as possible, if you allow to use "<", "≤" or "≠" symbols. Not tomorrow, but in some future.

[Jan Rheinlaender]

Ijust looked at the GiNaC code and there is no special handling for inequalities at all. So if iMath needs it then I need to implement it myself.

In any case, we can only handle simple cases, because what happens if you multiply (a<b) with c, where c does not have a value (yet)?

The real reason I enabled inequalities some time ago was because of the ifelse() function.