Function powers_starting_from

utils/src/ff.rs:88–97

Powers of a finite field as `[start, start*exp, start * exp^2, .. start * exp^{num-1}]`

(start: F, exp: &F, num: u32)

/// Powers of a finite field as `[start, start*exp, start * exp^2, .. start * exp^{num-1}]`
pub fn powers_starting_from<F: Field>(start: F, exp: &F, num: u32) -> Vec<F> {
    let mut powers = Vec::with_capacity(num as usize);
    if num > 0 {
        powers.push(start);
        for i in 1..num as usize {
            powers.push(powers[i - 1] * exp);
        }
    }
    powers
}

/// SUM of a geometric progression
/// SUM a^i = (1 - a^n) / (1 - a) = -(1-a^n)/-(1-a)