logarithm in OpenSSL

[Niklas Niere]

Thank you for the answer. We are using the Makefile from OpenSSL to 
compile our feature as it changes OpenSSL directly. As I understood it, 
we would have to import another number library to compile our code with 
the standard OpenSSL settings and using the logarithm, correct?

On 2019-07-24 6:51 p.m., Guido Vranken wrote:
> If you want to use the log() from math.h, then you must compile with 
> -lm, eg.: clang source.c -lm
>
> The log() in math.h only supports floating point numbers. If you 
> require computing logarithms of bignums, try https://www.mpfr.org/
>
> On Wed, Jul 24, 2019 at 6:39 PM Niklas Niere 
> <nniklas at mail.uni-paderborn.de <mailto:nniklas at mail.uni-paderborn.de>> 
> wrote:
>
>     Hello,
>
>     we are implementing a TLS 1.3 feature into OpenSSL to get an idea
>     of how
>     well our feature performs in a concrete server library. In the
>     feature,
>     we want to use the log function.
>
>     When we try to use the log function from the math.h header, OpenSSL
>     won't compile with the statement that 'log' is a reference to an
>     undefined function. The BigNum library from OpenSSL does also not
>     seem
>     to offer a log function.
>
>     We suspect that the compile error comes from the fact that OpenSSL is
>     C90 compatible but are unsure. Does anyone know how to compute the
>     logarithm of a number in OpenSSL?
>
>     Thanks,
>     Niklas
>
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