Inconsistent evaluation of some expressions

[zkorz]

I am having difficulty with consistency is evaluating expressions.

For example:

var input =  KAS.parse("(3x+7)/(x+4)").expr;
var output = KAS.parse("(-3x-7)/(-x-4)").expr;
input.compare(output)

Should evaluate to true every time, but it only does so 90% of the time.

The following simulation run in any browser will show the problem:

var countTrue = 0; 
var countFalse = 0; 
for(var i = 0; i < 1000; i++) { 
    if(KAS.parse("(3x+7)/(x+4)").expr.compare(KAS.parse("(-3x-7)/(-x-4)").expr)) 
       countTrue++; 
    else 
       countFalse++;
} 
console.log('Count true: '+countTrue); 
console.log('Count false: '+countFalse);

Any help would be greatly appreciated.

[zkorz]

I figured out the issue. I changed one line in your source code and it works 100% of the time for equivalent expressions. There were times two equal expressions were evaluating to +Infinity and the other to -Infinity. Perhaps it is a round off issue like 0.00001/0 vs. -0.00001/0. The numerators are very close to each other but the results themselves are polar opposites of the number line.

var equalNumbers = function(num1, num2) {\n
    var delta = getDelta(num1, num2);
    return ((num1 === num2) || /* needed if either is +/- Infinity */
                (!isFinite(num1) && !isFinite(num2)) ||  /* I added this line */
                (isNaN(num1) && isNaN(num2)) ||
                (delta < Math.pow(10, -TOLERANCE)));
};

[kevinbarabash]

90% of the time

That's worrisome. Thanks for reporting this.

[trkern]

KAS.compare(KAS.parse("(sqrt(b^2-4)/2)^2").expr,KAS.parse("b^2/4-1").expr).equal returns true about 44% of the time.