Experimental Physics and Industrial Control System
Marty,
Thanks for your reply concerning the accuracy of
converting a Double to a String within EPICS.
I have done some further investigation and found that
by setting PREC to 7 in the incoming record (the record
which is receiving the double), I do indeed get an accuracy
of 7 decimal places. However, changing PREC to 15 (which you
might want for the accuracy of a double),
I discovered that the double goes through with an
accuracy of only 5 decimal places!
The problem lies within the code for "cvtDoubleToString" inside
libCom/cvtFast.c. Line 150 of cvtFast.c shows that the value will
be converted to a string as follows, whenever PREC > 8.
sprintf(pstr_value,"%12.5e\0",flt_value);
I would say that "%12.5e" format is not what we want in
this case. Are there any plans to change this to something
which greater reflects the accuracy expected of a double?
Andy
==========================================================================
Andy Foster
Royal Greenwich Observatory Tel: 44 (0)1223 374899 (direct)
Madingley Road E-mail: [email protected]
Cambridge
CB3 0HA
UK
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