Re: [Geographiclib-users] Find S12 using planimeter

[Charles K. <cha...@sr...>]

On 09/25/2014 04:40 PM, Mike Toews wrote:
> On 26 September 2014 03:56, Charles Karney <cha...@sr...> wrote:
>> You've got the MPFR requirements wrong...
>>
>> I'm using 3.1.2 but I would expect 3.1.0 to be OK too.  The 3.5.9 refers
>> to MPFR C++ which is a single header file (mpreal.h) you can stick into
>> the include directory.
>>
>
> OK thanks, I see the distinction between MPFR and MPFR C++; I had only
> installed the former. The later is not yet available in Debian stable,
> but is in testing (Debian Jessie). Regardless, it's a simple header
> file that can easily be downloaded and placed in /usr/local/include,
> and the project compiles normally.
>
> -Mike
>

The way to set the MPFR precision in the utility programs is as follows:

   echo '0 0;0 90;90 0' |
   tr ';' '\n' |
   GEOGRAPHICLIB_DIGITS=1000 tools/Planimeter -p 100

which means calculate with 1000 bits of precision and print the results
with ~100 decimal digits of precision.

   --Charles