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Re: Support of log10?
From: |
Peng Yu |
Subject: |
Re: Support of log10? |
Date: |
Wed, 23 Jun 2021 20:30:48 -0500 |
> | 16.3 Arbitrary-Precision Arithmetic Features in gawk
>
> | By default, gawk uses the double-precision
> | floating-point values [...] However, if it was
> | compiled to do so, and the -M command-line
> | option is supplied, gawk uses the GNU MPFR and
> | GNU MP (GMP) libraries
The above sentence is not clear. What is the difference between MPFR
and GMP? Why both of them need to be used?
> for arbitrary-precision
> | arithmetic on numbers.
>
> > echo 3 | gawk -M -v 'OFS=\t' -v OFMT=%.20g \
> -e 'function log10(x) { return log(x)/log(10); } \
> { print "log10(" 10^$1 ")", log10(10^$1) }'
>
> log10(1000) 3
The drawback of -M is that it can be many times slow? In this sense
float log10 function may still be useful?
time gawk -e 'function log10(x) { return log(x)/log(10); } {
for(i=1;i<=1000000;++i) log10(10^$1) }' <<< 3
real 0m0.180s
user 0m0.176s
sys 0m0.002s
time gawk -M -e 'function log10(x) { return log(x)/log(10); } {
for(i=1;i<=1000000;++i) log10(10^$1) }' <<< 3
real 0m2.842s
user 0m2.838s
sys 0m0.003s
> See also footnote 98 and its referencing text.
Where is footnote 98?
--
Regards,
Peng
- Support of log10?, Peng Yu, 2021/06/23
- Re: Support of log10?, Neil R. Ormos, 2021/06/23
- Re: Support of log10?,
Peng Yu <=
- Re: Support of log10?, Eli Zaretskii, 2021/06/24
- Re: Support of log10?, Peng Yu, 2021/06/24
- Re: Support of log10?, Ed Morton, 2021/06/24
- Re: Support of log10?, Eli Zaretskii, 2021/06/24
- Re: Support of log10?, Peng Yu, 2021/06/24
Re: Support of log10?, Nelson H. F. Beebe, 2021/06/23
Re: Support of log10?, arnold, 2021/06/24