This is a Correlation Matrix. The description of this type of graph is quite mathematical and can be confusing for the non-mathematical thinker. A Correlation Matrix depicts the correlation among M variables (therefore, there is not a set number of variables that must be depicted in this type of graph). The diagonal elements are always equal to 1.00. The diagonal elements are the correlations of variables with themselves. This particular example depicts a calculated protein correlation matrix for phage T7.
