RosettaCodeData/Task/Averages-Root-mean-square/ALGOL-68/averages-root-mean-square.alg
2013-04-10 14:58:50 -07:00

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# Define the rms PROCedure & ABS OPerators for LONG... REAL #
MODE RMSFIELD = #LONG...# REAL;
PROC (RMSFIELD)RMSFIELD rms field sqrt = #long...# sqrt;
INT rms field width = #long...# real width;
PROC crude rms = ([]RMSFIELD v)RMSFIELD: (
RMSFIELD sum := 0;
FOR i FROM LWB v TO UPB v DO sum +:= v[i]**2 OD;
rms field sqrt(sum / (UPB v - LWB v + 1))
);
PROC rms = ([]RMSFIELD v)RMSFIELD: (
# round off error accumulated at standard precision #
RMSFIELD sum := 0, round off error:= 0;
FOR i FROM LWB v TO UPB v DO
RMSFIELD org = sum, prod = v[i]**2;
sum +:= prod;
round off error +:= sum - org - prod
OD;
rms field sqrt((sum - round off error)/(UPB v - LWB v + 1))
);
main: (
[]RMSFIELD one to ten = (1,2,3,4,5,6,7,8,9,10);
print(("crude rms(one to ten): ", crude rms(one to ten), new line));
print(("rms(one to ten): ", rms(one to ten), new line))
)