How to force calculation?

[Andreas Piculell]

Hi.

I was wondering, is it possible to enforce "simplest form possible" on calculations?

Because when i was messing around with fractions, i noticed that the engine evaluates the fractions as equal (which they also are), but is there a way to enforce the most simple form on an expression? For example the engine evaluates this to true:

3-5+8/6 == -2/3

And this

6/8 == 3/4

Is there a way (or function) to make sure that this evaluates to False, and is only True if it is indeed the most simple form of the fraction?

The same applies to this example:

Simplify(x+2x+6) == x+2x+6

This evaluates to True also, but is there a way to make sure it does not unless the right answer is provided? (6+3x OR 3x+6) ?

Many thanks in advance

[Axel Kramer]

Not sure what you want to achieve?

Do you have some sample codes?

Did you try Hold() for letting an expression unevaluated?

Hold(expr)

Did you try Trace() for getting the evaluation steps

Trace(expr)

• SameQ
• UnsameQ

[Andreas Piculell]

Well the "Hold(expr)" did sound like the thing i needed, but i just tried it, and it does not work in my program. Also, i cannot find it here: https://bitbucket.org/axelclk/symja_android_library/src/f4292c0d129d/symja_android_library/doc/functions/?at=master

SameQ is the one i am using now, and SameQ(Simplify(6/8), 6/8) == True, which is my problem. I only want SameQ to be true, if the second argument is the most simple answer of the first argument. For example, i want this to be the case:

SameQ(Simplify(6/8), 6/8) == False

And

SameQ(Simplify(6/8), 3/4) == True

It did sound like a good answer to use "Hold", such that

SameQ(Simplify(6/8), Hold(6/8)) == False

But it just made everything turn out false, also

SameQ(Simplify(6/8), Hold(3/4)) == False

And i still what that to be true.

[Axel Kramer]

In commmit #220ba1f I made some changes for Hold() and HoldForm.

HoldForm(6/8)==6/8

will evaluate to

6/8==3/4

and

Hold(6/8)==3/4

to

Hold(6/8)==3/4

It would probably help if you show your source code, so that on "Java level" it could be easier to get what you want?

[Andreas Piculell]

And does HoldForm(6/8)===3/4 evaluate to True of False after your changes?

In order for me to try it out i would need a ned JAR build with the changes, since i do not have eclipse and ANT here at the moment.

[Axel Kramer]

Here you can find the latests Maven Symja snapshot

[Andreas Piculell]

Alright i finally got to tryout the nye core update, and it is not doing what i expected.

i have HoldForm(3/4) === 3/4 evaluate to False.

What i need is that if i call HoldForm(3/4) === 3/4 is will be True, but if i call HoldForm(6/8) === 3/4 it will evaluate to False, since it is not the most simple form.

My Java code is actually just comparing the answer with the result like this:

// instantiate new expression evaluator engine instance
ExprEvaluator util = new ExprEvaluator(false, 100);

// get correct result by evaluating the formal
IExpr result = util.evaluate(expression.getFormal());

// evaulate if answer was correct
IExpr comparison = util.evaluate("HoldForm("+getUserAnswer() + ") === " +result.toString() );

I hope that helps to see what i mean :)

[Axel Kramer]

Please use the Github issue tracker to open a new issue if this issue shouldn't be closed Github issues