There are duplicate and inconsistent mathematical notations

[mbaudin47]

What is the idea?

New mathematical notations were successfully introduced in #2574.

These changes were introduced in [math_notations.sty](https://github.com/openturns/openturns/blob/master/python/doc/math_notations.sty]. But these notations are not entirely consistent.

• The input distribution is defined by:

openturns/python/doc/math_notations.sty

Line 29 in 7481e77

\newcommand{\inputMeasure}{\mu_{\inputRV}} % The distribution of the input random vector of the model

or:

openturns/python/doc/math_notations.sty

Line 55 in 7481e77

\newcommand{\inputProbabilityDensityFunction}{f}

or:

openturns/python/doc/math_notations.sty

Line 71 in 7481e77

\newcommand{\pdf}{f_{\un{X}}(\un{x})}

• The input domain does not use the \set macro:

openturns/python/doc/math_notations.sty

Line 23 in 7481e77

\newcommand{\inputDomain}{\mathcal{D}} % Input domain of the model

It is not consistent with the physical input space:

openturns/python/doc/math_notations.sty

Line 50 in 7481e77

\newcommand{\physicalInputSpace}{\set{X}}

• The output domain is defined as:

openturns/python/doc/math_notations.sty

Line 52 in 7481e77

\newcommand{\physicalOutputSpace}{\set{Y}}

but this could altenatively be named outputDomain.

Why is this needed?

Update math_notations.sty and the file that use these macros.

Additional Context

No response