Method validate

docs/app/js/sanddance-app.js:69344–69348

()

        return this;
    }
    validate() {
        let valid = this.length === this.ELEMENTS;
        for(let i = 0; i < this.ELEMENTS; ++i)valid = valid && Number.isFinite(this[i]);
        return valid;
    }
    sub(a) {
        return this.subtract(a);
    }