  A C++ library, named ZKCM, has been developed for the purpose of
multiprecision matrix calculations, which is based on the GNU MP and MPFR
libraries. It is especially convenient for writing programs involving
tensor-product operations, tracing-out operations, and singular-value
decompositions. Its extension library, ZKCM_QC, for simulating quantum
computing has been developed using the time-dependent matrix-product-state
simulation method. This report gives a brief introduction to the libraries with
sample programs.
