Easing to zero - success

- (void)testEasing {
    double steps = 10;

    double start = 0;
    double end = 100;
    NSLog(@"Test %0.f to %0.f", start, end);
    for (double i = 0; i < steps; i++) {
        [self easeInOut:i b:start c:end d:steps];
    }

    start = 100;
    end = 0;
    NSLog(@"Test %0.f to %0.f", start, end);
    for (double i = 0; i < steps; i++) {
        [self easeInOut:i b:start c:end d:steps];
    }

}

// Source: http://gizma.com/easing/
- (double)easeInOut:(double)t b:(double)b c:(double)c d:(double)d {

    if (t>d) return c;

    BOOL reverse = NO;
    if (c < b) {
        reverse = YES;
        double newc = b;
        b = c;
        c = newc;
    }

    NSInteger logStep = (NSInteger)t;
    double result;
    t /= d/2;
    if (t < 1) {
        result = c/2*t*t*t + b;
        if (reverse) result = c - result;
        NSLog(@"%ld: %f = %f/2*%f*%f*%f + %f", (long)logStep, result, c, t, t, t, b);
        return result;
    };
    t -= 2;
    result = c/2*(t*t*t + 2) + b;
    if (reverse) result = c - result;
    NSLog(@"%ld: %f = %f/2*(%f*%f*%f + 2) + %f", (long)logStep, result, c, t, t, t, b);
    return result;
}

// Resulting output
//
// Test 0 to 100
// 0: 0.000000 = 100.000000/2*0.000000*0.000000*0.000000 + 0.000000
// 1: 0.400000 = 100.000000/2*0.200000*0.200000*0.200000 + 0.000000
// 2: 3.200000 = 100.000000/2*0.400000*0.400000*0.400000 + 0.000000
// 3: 10.800000 = 100.000000/2*0.600000*0.600000*0.600000 + 0.000000
// 4: 25.600000 = 100.000000/2*0.800000*0.800000*0.800000 + 0.000000
// 5: 50.000000 = 100.000000/2*(-1.000000*-1.000000*-1.000000 + 2) + 0.000000
// 6: 74.400000 = 100.000000/2*(-0.800000*-0.800000*-0.800000 + 2) + 0.000000
// 7: 89.200000 = 100.000000/2*(-0.600000*-0.600000*-0.600000 + 2) + 0.000000
// 8: 96.800000 = 100.000000/2*(-0.400000*-0.400000*-0.400000 + 2) + 0.000000
// 9: 99.600000 = 100.000000/2*(-0.200000*-0.200000*-0.200000 + 2) + 0.000000
//
// Test 100 to 0
// 0: 100.000000 = 100.000000/2*0.000000*0.000000*0.000000 + 0.000000
// 1: 99.600000 = 100.000000/2*0.200000*0.200000*0.200000 + 0.000000
// 2: 96.800000 = 100.000000/2*0.400000*0.400000*0.400000 + 0.000000
// 3: 89.200000 = 100.000000/2*0.600000*0.600000*0.600000 + 0.000000
// 4: 74.400000 = 100.000000/2*0.800000*0.800000*0.800000 + 0.000000
// 5: 50.000000 = 100.000000/2*(-1.000000*-1.000000*-1.000000 + 2) + 0.000000
// 6: 25.600000 = 100.000000/2*(-0.800000*-0.800000*-0.800000 + 2) + 0.000000
// 7: 10.800000 = 100.000000/2*(-0.600000*-0.600000*-0.600000 + 2) + 0.000000
// 8: 3.200000 = 100.000000/2*(-0.400000*-0.400000*-0.400000 + 2) + 0.000000
// 9: 0.400000 = 100.000000/2*(-0.200000*-0.200000*-0.200000 + 2) + 0.000000