For future development

[kousuke-nakano]

• Add comments in the codes with the ford format (Clarify meanings of variables.)
• Use only.
• Use Intent(in), Intent(out), Intent(inout)
• Improve the outputs
• Integrate all subroutines and functions into modules.

[kousuke-nakano]

I will start from

• Use only
• Use Intent(in), Intent(out), Intent(inout)