Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Linear transformations of frequency distribution space. A substitution matrix imposes a linear transformation M that maps each observed frequency vector f to a pseudocount vector g, and all of frequency distribution space to the smallest simplex shown. For values of α between 0 and 1, the use of pseudocounts imposes a linear transformation 
that maps f to a point q on the line between f and g, and the frequency distribution space to the intermediate simplex shown.
