Error Handling¶ ↑
Error codes¶ ↑
The GSL routines report an error whenever they cannot perform the task requested of them. For example, a root-finding function would return a non-zero error code if could not converge to the requested accuracy, or exceeded a limit on the number of iterations. Situations like this are a normal occurrence when using any mathematical library and you should check the return status of the functions that you call.
Whenever a routine reports an error the return value specifies the type of error. The return value is analogous to the value of the variable errno in the C library. The caller can examine the return code and decide what action to take, including ignoring the error if it is not considered serious.
The error code numbers in GSL as GSL_EDOM are defined in
Ruby/GSL as Ruby constants under the GSL module. Here are some
of them:
-
GSL::EDOM- Domain error; used by mathematical functions when an argument value does not fall into the domain over which the function is defined (likeEDOMin the C library) -
GSL::ERANGE- Range error; used by mathematical functions when the result value is not representable because of overflow or underflow (likeERANGEin the C library) -
GSL::ENOMEM- No memory available. The system cannot allocate more virtual memory because its capacity is full (likeENOMEMin the C library). This error is reported when a GSL routine encounters problems when trying to allocate memory with malloc. -
GSL::EINVAL- Invalid argument. This is used to indicate various kinds of problems with passing the wrong argument to a library function (likeEINVALin the C library).
Error handler¶ ↑
In Ruby/GSL, the default GSL error handler is replaced by an other one
which calls rb_raise(). Thus whenever a GSL routine reports a
fatal error, a Ruby Exception is generated.
-
GSL::set_error_handler(proc)
-
GSL::set_error_handler { |reason, file, line, errno| … }
This replaces the Ruby/GSL default error handler by a user-defined handler given by a Proc object
procor a block.