* double values. All numbers
* with a smaller absolute value
* will be printed as zero.
+ *
+ * The default value for this
+ * threshold is zero,
+ * i.e. numbers are printed
+ * according to their real value.
+ *
+ * This feature is mostly useful
+ * for automated tests: there,
+ * one would like to reproduce
+ * the exact same solution in
+ * each run of a
+ * testsuite. However, subtle
+ * difference in processor,
+ * operating system, or compiler
+ * version can lead to
+ * differences in the last few
+ * digits of numbers, due to
+ * different rounding. While one
+ * can avoid trouble for most
+ * numbers when comparing with
+ * stored results by simply
+ * limiting the accuracy of
+ * output, this does not hold for
+ * numbers very close to zero,
+ * i.e. zero plus accumulated
+ * round-off. For these numbers,
+ * already the first digit is
+ * tainted by round-off. Using
+ * the present function, it is
+ * possible to eliminate this
+ * source of problems, by simply
+ * writing zero to the output in
+ * this case.
*/
void threshold_double(const double t);