There is an ongoing outage on the primary CPAN mirror. It is possible to work around the issue by using MetaCPAN as a mirror.

MOZNION / Math-PSNR-0.02 / Changes 
Revision history for Math-PSNR

0.02  Sat Jan 12 15:43:12 JST 2013
        Enabled a caching function.

0.01  Wed Jan  9 14:32:48 JST 2013
        Initial release.