Trace distance

The command below calculates the trace distance between the two matrices $A$ and $B$ read from respective files of fileA and fileB saved by the ``msave'' command (or ``RDOsave'' etc.).

trdist(fileA, fileB);

The trace distance between (N,N) density matrices $A$ and $B$ is defined by

$$\begin{split}D(A,B)&=\frac{1}{2}\mathrm{Tr}\vert A-B\vert\\ &=\frac{1}{2}\mathrm{Tr}\sqrt{(A-B)^\dagger(A-B)}. \end{split}$$