/* Dot product, in Jsish */
function dot_product(ary1, ary2) {
    if (ary1.length != ary2.length) throw "can't find dot product: arrays have different lengths";
    var dotprod = 0;
    for (var i = 0; i < ary1.length; i++) dotprod += ary1[i] * ary2[i];
    return dotprod;
}

;dot_product([1,3,-5],[4,-2,-1]);
;//dot_product([1,3,-5],[4,-2,-1,0]);

/*
=!EXPECTSTART!=
dot_product([1,3,-5],[4,-2,-1]) ==> 3
dot_product([1,3,-5],[4,-2,-1,0]) ==>
PASS!: err = can't find dot product: arrays have different lengths
=!EXPECTEND!=
*/