Rounding to the Nearest Reciprocal

[Eddie W. Shore]

The program ROUNDRCP rounds a number to the nearest 1/n. This function can come in handy in several applications, for example, when working with construction or measuring, when have to round results to the nearest eighth (1/8), inch (1/12) or sixteenth (1/16).

Code:

EXPORT ROUNDRCP(a,n)
BEGIN
// Round a to the nearest 1/n
// 2017-11-21 EWS
LOCAL w;
w:=FP(ABS(a))*n;
w:=ROUND(w,0);
RETURN IP(a)+SIGN(a)*(w/n);
END;

Round π to the nearest 1/4:
ROUNDRCP(π, 4): 3.25 = 13/4

Round e^2 to the nearest 1/100:
ROUNDRCP(e^2, 100): 7.39 = 739/100

Round 1/4 + 2/7 + 3 1/3 to the nearest 1/16:
ROUNDRCP(1/4 + 2/7 + 3 + 1/3, 16): 3.875 = 31/8