* you need to use separate random number facilities for separate
* threads, rather than this global function. For example, the C++11
* standard offers such objects, as does BOOST.
+ *
+ * @note Like the system function rand(), this function produces
+ * the same sequence of random numbers every time a program is
+ * started. This is an important property for debugging codes,
+ * but it makes it impossible to really verify statistics
+ * properties of a code. For rand(), you can call srand() to
+ * "seed" the random number generator to get different sequences
+ * of random numbers every time a program is called. However, this
+ * function does not allow seeding the random number generator.
+ * If you need this, as above, use one of the C++ or BOOST
+ * facilities.
*/
double
generate_normal_random_number (const double a,