Abstract: A variable retrieving unit refers to variable relation information and variable definition information held in an analysis result storing unit and retrieves variables which directly relate to a variable designated by a retrieval designating unit. A display unit displays a variable retrieval result by the variable retrieving unit in a form such that the variable retrieval result can be used for designation for re-retrieval by the retrieval designating unit.

Abstract: A restricting condition extracting unit analyzes an error determination portion included in a program to be analyzed and extracts a restricting condition of a particular variable. A variable categorizing unit analyzes the relation among variables used in an executable statement in the program to be analyzed and categorizes the variables corresponding to the analyzed result. A domain definition extracting unit outputs domain relation information representing a domain to which a plurality of variables belong and the relation among variables that belong to the domain using the output of the restricting condition extracting unit and the variable categorizing unit. The domain definition information is graphically displayed so that the user can easily understand the content thereof.

Abstract: A variable type analyzing unit detects the data types of each variable. A variable length analyzing unit detects the length of each variable. A partial reference unit detects the range of a partial reference when part of a variable is referred to. An internal layout analyzing unit checks the range to which data is actually referred and to which data is actually assigned based on the information on each variable obtained by the above units. A domain analyzing unit categorizes variables used in a target program by domain based on the ranges.