Corrected some syntax errors in the doxygen markup that prevented the documentation to compile

src/include/sph_subs.h

@@ -127,9 +127,9 @@ void mmulc(std::complex<double> *vint, double **cmullr, double **cmul);
 /*! \brief Starting point for Bessel function magnitude.
  *
  * This function determines the starting point for backward recurrence such that
- * the magnitude of all \f$J\f$ and \$j\f$ functions is of the order of \f$10^{-mp}\f$.
+ * the magnitude of all \f$J\f$ and \f$j\f$ functions is of the order of \f$10^{-mp}\f$.
  *
- * \param x: `double` Absolute value of the argumetn to \f$J\f$ or \$j\f$.
+ * \param x: `double` Absolute value of the argumetn to \f$J\f$ or \f$j\f$.
  * \param mp: `int` Requested order of magnitude.
  * \return result: `int` The necessary starting point.
  */
@@ -138,7 +138,7 @@ int msta1(double x, int mp);
 /*! \brief Starting point for Bessel function precision.
  *
  * This function determines the starting point for backward recurrence such that
- * all \f$J\f$ and \$j\f$ functions have `mp` significant digits.
+ * all \f$J\f$ and \f$j\f$ functions have `mp` significant digits.
  *
  * \param x: `double` Absolute value of the argumetn to \f$J\f$ or \$j\f$.
  * \param n: `int` Order of the function.
@@ -256,7 +256,7 @@ void rkt(
 
 /*! \brief Spherical Bessel functions.
  *
- * This function computes the spherical Bessel functions \f$y\$. It adopts the `SPHJY`
+ * This function computes the spherical Bessel functions \f$y\f$. It adopts the `SPHJY`
  * implementation of the `specfun` library.
  *
  * \param n: `int` Order of the function (from 0 up).