Binary search the return value of f for the closest value v is between starting with min going to max.

searchhighlow

var searchHighLow = function(v,f,min,max) {

	var t, dat;

	for (;;) {
		dat = f(min);
		if(dat === v) return [min,min];
		t = (min + max) >> 1;
		dat = f(t);
		if(dat === v) return [t,t];
		if(dat < v) min = t;

		dat = f(max);
		if(dat === v) return [max,max];
		t = (min + max) >> 1;
		dat = f(t);
		if(dat === v) return [t,t];
		if(dat > v) max = t;

		if((max - min) < 17) {
			var tmin = min, tmax = max
			dat = f(tmin);
			if(dat > v) {
				tmin = undefined;
			} else {
				t = tmin;
				while(t <= max && (dat = f(t)) <= v ) {
					if(dat === v) return [t,t];
					tmin = t
					t++;
				};
			}

			dat = f(tmax);
			if(dat < v) {
				tmax = undefined;
			} else {
				t = tmax;
				while(t >= min && (dat = f(t)) >= v ) {
					if(dat === v) return [t,t];
					tmax = t;
					t--;
				};
			}
			return [tmin,tmax];
		}
	}
}