Function plonk_gadgets::scalar::conditionally_select_zero

pub fn conditionally_select_zero(
    composer: &mut StandardComposer, 
    x: Variable, 
    select: Variable
) -> Variable

Conditionally selects the value provided or a zero instead. NOTE that the select input has to be previously constrained to be either one or zero.

Performs:

x’ = x if select = 1 x’ = 0 if select = 0