z2cent: Express z-scores as centile character strings for plotting
Description
Converts z-scores, typically defining centiles in a growth chart, to
character strings that can be used to label the centile curves.
Usage
z2cent(z)
Value
A character string is returned, the same length as z. Z-scores between
the 1st and 99th centile are converted to centiles with one or two significant
figures (lower tail) or to their complement (upper tail). For larger z-scores
in absolute value the character consists of "SDS" appended to the z-score
rounded to one decimal place.