Function nominal

Calculates the nominal annual interest rate, given the effective rate and the number of compounding periods per year.

Remarks:

• npery is truncated to an integer.
• If either argument is nonnumeric, an error is thrown.
• If effectRate <= 0 or if npery < 1, an error is thrown.
• nominal() is related to effect() through effectiveRate = (1 + (nominalRate / npery)) * npery - 1.