  The concept of temperature is one of the key ideas in describing the
thermodynamical properties of a physical system. In classical statistical
mechanics of ideal gases, the notion of temperature can be described in two
different ways, the kinetic temperature and the thermodynamic temperature. For
the Boltzmann distribution, the two notions lead to the same result. However,
for a general probability density function, while the kinetic temperature has
been commonly used, there appears to be no corresponding general definition of
thermodynamic temperature. In this paper, we propose such a definition and show
that it is connected to the Fisher information associated with the distribution
of the momenta.
