HalfdanJ

export default function LowpassFilter(Fc) {
    var Q = 0.707;
    var K = Math.tan(Math.PI * Fc);
    var norm = 1 / (1 + K / Q + K * K);
    this.a0 = K * K * norm;
    this.a1 = 2 * this.a0;
    this.a2 = this.a0;
    this.b1 = 2 * (K * K - 1) * norm;
    this.b2 = (1 - K / Q + K * K) * norm;

kylemcdonald

// group of for loops with waiting
int m, n;
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,0), ^{
    // before all parallel m
    dispatch_apply(m, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^(size_t i) {
        // parallel m code with i for index
    });
    // after all parallel m
});