Function apr 

pub fn apr(
    apr: f64,
    compounding_periods_in_year: u32,
) -> FinanceResult<ConvertRateSolution>

Helper function to convert a quoted annual rate (APR) into all possible conversions (EAR, EPR).

Errors

Returns FinanceError if compounding_periods_in_year < 1 or rate is non-finite.