diff --git a/lib/potential/gm_data.cpp b/lib/potential/gm_data.cpp
index 3ce865e..fbf808c 100644
--- a/lib/potential/gm_data.cpp
+++ b/lib/potential/gm_data.cpp
@@ -343,7 +343,7 @@ void gctl::power_spectrum(array<double> &P, const array<double> &C, const array<
 {
     if (n < 0 || n >= N || C.size() < (N + 1)*(N + 2)/2 || S.size() < (N + 1)*(N + 2)/2)
     {
-        throw std::runtime_error("[gctl::power_spectrum_shc] Invalid input parameters.");
+        throw std::runtime_error("[gctl::power_spectrum] Invalid input parameters.");
     }
 
     P.resize(N - n + 1, 0);
diff --git a/lib/potential/gm_data.h b/lib/potential/gm_data.h
index c48ae07..3bf2b03 100644
--- a/lib/potential/gm_data.h
+++ b/lib/potential/gm_data.h
@@ -230,8 +230,9 @@ namespace gctl
      * @param n_max Maximum spherical harmonic degree to compute.
      * @param P A vector of all associated Legendgre polynomials evaluated at co_lati up to nMax. 
      * The lenght must by greater or equal to (n_max+1)*(n_max+2)/2. The coefficients are stored 
-     * in a degree major order.
-     * @param dP Derivative of P with respect to latitude
+     * in a degree major order. The index of the coefficient at degree n and order m is n*(n+1)/2 + m.
+     * @param dP Derivative of P with respect to latitude. The coefficients are stored in the same
+     * order as in P.
      */
     void schmidt_legendre(double co_lati, int n_max, array<double> &P, array<double> &dP);
     
@@ -239,8 +240,8 @@ namespace gctl
      * @brief Calculate the power spectrum of given spherical harmonic coefficients.
      * 
      * @param P Returned power spectrum
-     * @param C Cosine coefficients strats from 0 order 0 degree up to least N order N degree
-     * @param S Sine coefficients strats from 0 order 0 degree up to least N order N degree
+     * @param C Cosine coefficients strats from 0 order 0 degree up to at least N order N degree
+     * @param S Sine coefficients strats from 0 order 0 degree up to at least N order N degree
      * @param R Reference radius (usually is 6371.2 km)
      * @param r Observation radius
      * @param n Strat order
@@ -248,6 +249,6 @@ namespace gctl
      */
     void power_spectrum(array<double> &P, const array<double> &C, const array<double> &S, 
         double R, double r, int n, int N);
-}
+};
 
 #endif // _GCTL_GM_DATA_H
\ No newline at end of file