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 <nnik...@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 > >
