exponential-ease-in-out.js

// Modeled after the piecewise exponential
// y = (1/2)2^(10(2x - 1))         ; [0,0.5)
// y = -(1/2)*2^(-10(2x - 1))) + 1 ; [0.5,1]
function exponentialEaseInOut (p) {
    if(p === 0.0 || p === 1.0) return p;
    if(p < 0.5) {
        return 0.5 * Math.pow(2, (20 * p) - 10);
    } else {
        return -0.5 * Math.pow(2, (-20 * p) + 10) + 1;
    }
}