This function converts numeric column(s) of a data frame object, matrix or vector from double precision to single precision, e.g. to avoid a warning from MLwiN which currently only stores data in single precision.
double2singlePrecision(x)A data.frame object, matrix or vector to be converted. Column(s)
of these objects will be ignored during conversion if they are not
numeric.
An object of numerical values in single precision will be returned.