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<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial>Hi David, thanks for posting this! I just
took a quick skim through <U>P1467R4.html</U> ; one sentence
caught my eye:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial> <SPAN
style="FONT-SIZE: medium; FONT-FAMILY: sans-serif; WHITE-SPACE: normal; WORD-SPACING: 0px; TEXT-TRANSFORM: none; FLOAT: none; FONT-WEIGHT: 400; COLOR: rgb(0,0,0); FONT-STYLE: normal; ORPHANS: 2; WIDOWS: 2; DISPLAY: inline !important; LETTER-SPACING: normal; BACKGROUND-COLOR: rgb(255,255,255); TEXT-INDENT: 0px; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial">When
an implementation supports both binary and decimal floating-point, the
conversion </SPAN></FONT></SPAN><SPAN class=171053718-15062020><FONT
color=#0000ff size=2 face=Arial><SPAN
style="FONT-SIZE: medium; FONT-FAMILY: sans-serif; WHITE-SPACE: normal; WORD-SPACING: 0px; TEXT-TRANSFORM: none; FLOAT: none; FONT-WEIGHT: 400; COLOR: rgb(0,0,0); FONT-STYLE: normal; ORPHANS: 2; WIDOWS: 2; DISPLAY: inline !important; LETTER-SPACING: normal; BACKGROUND-COLOR: rgb(255,255,255); TEXT-INDENT: 0px; font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial">ranks
of a binary type and a decimal type will always be unordered, because neither
type’s set of values will be a subset of the other due to the different
radixes.<SPAN> </SPAN></SPAN></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial>This is not right; binary floating-point types can always
be a subset of appropriate decimal floating-point types because the latter have
a base of 5*2 (in C/C++ notation), so you can make an exact conversion using the
same number of digits. Decimal floating-point-types, however, cannot be
converted exactly to binary types (in general) because of that power of
five. <BR><BR>See <A
href="http://speleotrove.com/decimal/decifaq1.html"><FONT color=#0066cc size=3
face="Times New Roman">http://speleotrove.com/decimal/decifaq1.html</FONT></A> for
some of the background, rationale, etc.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial>Mike</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial> </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=171053718-15062020><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV><BR>
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dir=ltr>
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<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> Cfp-interest
[mailto:cfp-interest-bounces@oakapple.net] <B>On Behalf Of </B>David
Olsen<BR><B>Sent:</B> 15 June 2020 19:04<BR><B>To:</B> CFP<BR><B>Subject:</B>
[Cfp-interest 1638] C++ floating-point work<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=WordSection1>
<DIV>
<P class=MsoNormal>I am one of the authors of the C++ proposal P1467 “Extended
floating-point types”, which has similar goals to the _Float<I>N</I> work that
CFP is doing, in that it adds additional optional floating-point types to the
standard. The next revision of the proposal is available, <A
href="https://isocpp.org/files/papers/P1467R4.html">https://isocpp.org/files/papers/P1467R4.html</A>
(and also attached to this message). I welcome any feedback that CFP
might have, especially about the “C Compatibility” section, <A
href="https://isocpp.org/files/papers/P1467R4.html#c-compat">https://isocpp.org/files/papers/P1467R4.html#c-compat</A>
. Am I representing the C proposal correctly? Are there other
incompatibilities between the C and C++ proposals that I am not seeing?
The C++ Committee would like to do a better job than we have in the recent
past of keeping C and C++ from diverging unnecessarily, so we are soliciting
feedback from the C community while C++ proposals are still under development
when there is overlap between C and C++.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>--<o:p></o:p></P>
<P class=MsoNormal>David Olsen<o:p></o:p></P>
<P class=MsoNormal>NVIDIA HPC Compiler Team, WG21 member<o:p></o:p></P>
<P class=MsoNormal>Portland, Oregon<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P></DIV></DIV></BLOCKQUOTE></BODY></HTML>