# Tips

I made a program to calculate ‘A * B mod N’, where A, B and N are 64 bit integers.

Main problem is to avoid overflow when calculate ‘A * B’.

I searched a while and finally decided to use the interleaved modular multiplication method, which is used in the feild of electric circuit design.

~~I found some bugs when I tested corner cases, so I have to fix them [2018.9.2].~~
~~I think I’ve fixed them [2018.9.3].~~
I’ve just
improved it! [2018.9.5]

The program is shown below:

At the end of 2014, I was shocked at the progress of blind deblurring algorithm, so I studied the recent researches in this field.

I read many papers and made a system based on this paper: “Blind deconvolution using alternating maximum a posteriori estimation with heavy-tailed priors”.

I always use my customized statistics views shown below because the original ones provide only minimum information.

I show my tools in this post.

I made a CentOS vagrant box which contains GNOME desktop environment, so I will show how to use and to make it.

I’ll demonstrate how to relocate a tablespace directory without the reconstruction of databases.