  Rajagopalan and Sabir [nlin.CD/0104021 and Phys. Rev. E 63, 057201 (2001)]
recently discussed deterministic diffusion in a piecewise linear map using an
approach developed by Fujisaka et al. We first show that they rederived the
random walk formula for the diffusion coefficient, which is known to be the
exact result for maps of Bernoulli type since the work of Fujisaka and
Grossmann [Z. Physik B {\bf 48}, 261 (1982)]. However, this correct solution is
at variance to the diffusion coefficient curve presented in their paper.
Referring to another existing approach based on Markov partitions, we answer
the question posed by the authors regarding solutions for more general
parameter values by recalling the finding of a fractal diffusion coefficient.
We finally argue that their model is not suitable for studying intermittent
behavior, in contrast to what was suggested in their paper.
