Variable multiplication is not separed by *

[CaselIT]

The omission of the multiplication symbol between the variables makes it impossible to reparse a expression

example: algebra.parse('x*y').toString() returns xy that is considered as a single variable of name xy instead of x*y if reparsed.

My use case: Save the simplified version of an expression written by an user.

[CaselIT]

Probably the best option is to add an optional config object to the toString() method to modify its behaviour.

To show the multiplications between the variables a boolean option implicit can be added. So when toString({implicit: true}) is called the * will be shown

This way it's also easy to add new options.
I can work on a PR if you approve

[nicolewhite]

I am not sure I follow. While it is rendered as xy, they are still separate variables. Example:

var e = algebra.parse('x * y')
e.eval({x: 2}).toString();
"2y"
e.eval({y: 2}).toString();
"2x"

[CaselIT]

The problem arises if I try to re evaluate the toString output.
My use case is: The user inputs an expression, it is parsed and the parsed result is saved. Then I would like to be able to take the saved string at a later time and use it as input.

The problem is that since x * y is rendered as xy, the second time I parse xy this is considered as a single variable named xy.

In any case I've already solved this problem by writing a custom toString function, so if you like this can be closed.

[nicolewhite]

Ohh, I see. If you have already written the function, feel free to send a pull request with the implicit arg.

[CaselIT]

Ok, thanks 👍

[peekpeekpeekpeek]

algebra-0.2.6.min.js is missing the support for options passed to Term.toString.
When I put algebra-0.2.6.min.js through unminify.com I get this

Term.prototype.toString = function() {
                var e = "";
                for (var t = 0; t < this.coefficients.length; t++) {
                    var r = this.coefficients[t];
                    if (r.abs().numer !== 1 || r.abs().denom !== 1) {
                        e += " * " + r.toString()
                    }
                }
                e = this.variables.reduce(function(e, t) {
                    return e.concat(t.toString())
                }, e);
                e = e.substring(0, 3) === " * " ? e.substring(3, e.length) : e;
                e = e.substring(0, 1) === "-" ? e.substring(1, e.length) : e;
                return e
            };

Whilst the original in expressions.js dated June 2017 is

Term.prototype.toString = function(options) {
    var implicit = options && options.implicit;
    var str = "";

    for (var i = 0; i < this.coefficients.length; i++) {
        var coef = this.coefficients[i];

        if (coef.abs().numer !== 1 || coef.abs().denom !== 1) {
            str += " * " + coef.toString();
        }
    }
    str = this.variables.reduce(function (p, c) {
        if (implicit && !!p) {
            var vStr = c.toString();
            return !!vStr ? p + "*" + vStr : p;
        } else
            return p.concat(c.toString());
    }, str);
    str = (str.substring(0, 3) === " * " ? str.substring(3, str.length) : str);
    str = (str.substring(0, 1) === "-" ? str.substring(1, str.length) : str);

    return str;
};

Is algebra-0.2.6.min.js based on older source?