Function qip::measurement_ops::measure_prob

pub fn measure_prob<P: Precision>(
    n: u64, 
    measured: u64, 
    indices: &[u64], 
    input: &[Complex<P>], 
    input_offset: Option<u64>, 
    multithread: bool
) -> P

Calculate the probability of a given measurement. measured gives the bits (as a u64) which has been measured from the qubits at indices in the order supplied by indices. input gives the state from which to measure, representing a total of n qubits. And input_offset gives the actual index of the lowest indexed entry in input in case it's split across multiple vectors (as for distributed computation)

Keep in mind that qubits are big-endian to match kron product standards. |abc> means q0=a, q1=b, q2=c

Examples

use qip::state_ops::from_reals;
use qip::measurement_ops::measure_prob;

// Make the state |10>, index 0 is always |1> and index 1 is always |0>
let input = from_reals(&[0.0, 0.0, 1.0, 0.0]);

let p = measure_prob(2, 0, &[0], &input, None, false);
assert_eq!(p, 0.0);

let p = measure_prob(2, 1, &[0], &input, None, false);
assert_eq!(p, 1.0);

let p = measure_prob(2, 1, &[0, 1], &input, None, false);
assert_eq!(p, 1.0);

let p = measure_prob(2, 2, &[1, 0], &input, None, false);
assert_eq!(p, 1.0);