libpsdxx [WP][DOC]: add function call parameter documentation

src/libs/libpsdxx/psd.h

@@ -239,11 +239,25 @@ namespace psd {
                           const unsigned int& n_per_decade);
 
    /*! sample complex values on a logarithmic frequency axis
+    *
+    * \param s spectral values with uniform sampling along frequency axis
+    * \param f frequency values on a logarithmic scale like returned by
+    *          function log_frequency()
+    * \return series of sampled spectral values, where each sample of the
+    *         returned series corresponds to the frequency with the
+    *         corresponding index in \p f
     */
    TDCISeries::Tseries log_sampling(const TDCISeries::Tcoc& s,
                                     const TDseries::Tcoc& f);
 
    /*! sample real values on a logarithmic frequency axis
+    *
+    * \param s spectral values with uniform sampling along frequency axis
+    * \param f frequency values on a logarithmic scale like returned by
+    *          function log_frequency()
+    * \return series of sampled spectral values, where each sample of the
+    *         returned series corresponds to the frequency with the
+    *         corresponding index in \p f
     */
    TDISeries::Tseries log_sampling(const TDISeries::Tcoc& s,
                                    const TDseries::Tcoc& f);