CU {spreval}

Compute CU for Sprinkler Irrigation Systems

Description

Compute Christiansen Coefficient of Uniformity (CU or UC). Coefficient is based upon the average deviation from the mean value and the mean value.

Usage

CU(x)

Arguments

x

numeric array of catch can data. Array may include missing (NA) data. NA values will be removed in function.

Details

CU=100(1.0-\sum X/(nm))

where X=|z-m|; absolute deviation of catch z from average catch m based on n observations (catches).

Value

CU value in percentage. Note that CU can take on a negative value if the average deviation from the mean is greater than the mean.

Author(s)

Garry Grabow [e-mail]

References

Christiansen, J. E. 1942. Irrigation by sprinkling. California Agricultural Experiment Station Bulletin 670. Berkeley, Cal.: University of California.

Keller, J., and R. D. Bliesner. 2000. Sprinkler and Trickle Irrigation. Caldwell, N.J.: Blackburn Press. ISBN 1-930665-19-9.

See Also

DU,DU.lh

Examples

# data below are volumes caught in ml.  Catch cans must be of
# equal surface area at top when using volume data
x<-c(47,42,45,24,13,26,33,34,27,30,40,44,32,12,12)
xcu<-CU(x)
#round results
curnd<-round(xcu,2)
xcu
curnd