double vortex_xml_rpc_method_call_get_param_value_as_double ( XmlRpcMethodCall method_call,
int  position 

Allow to get current double value associated to the giveh XmlRpcMethodCall, at the given position for the parameter value.

If you are looking for a function to get the double inside a particular XmlRpcMethodValue, you can check vortex_xml_rpc_method_value_get_as_double.

method_call The method call where the double value will be retrieved.
position The parameter position to get.
A double value or 0.0 if fails. There is no easy way to get that the returned 0.0 value is because an error or due to that indeed, the parameter accessed have that value.