const double g_1 = cc_1 - i_1;
const double g_2 = cc - i_2;
/* The second factor is infinite, when the first is zero.
Therefore, evaluate the second, only when the first is non-zero */
const double g_1 = cc_1 - i_1;
const double g_2 = cc - i_2;
/* The second factor is infinite, when the first is zero.
Therefore, evaluate the second, only when the first is non-zero */