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Functions ‘R_atof’ and ‘R_strtod’ declared in header ‘R_ext/Utils.h’ are now documented in ‘Writing R Extensions’ and so formally part of the API.
‘as.numeric()’, ‘scan()’, ‘type.convert()’ and other places which use the internal C function ‘R_strtod’ now require a _non-empty_ digit sequence in a decimal or binary exponent. This aligns with the C/POSIX standard for ‘strtod’ and with ‘?NumericConstants’.