  We propose an analytical approximation for the energy spectrum of the scalar
induced gravitational waves (SIGWs) generated by a broken power-law power
spectrum, and find that both the asymptotic power-law tails and the
intermediate peak contribute distinct features to the SIGW spectrum. Moreover,
the broken power-law power spectrum has abundant near-peak features and our
results can be used as a near-peak approximation that covers a wide range of
models. Our analytical approximation is useful in the rapid generation of the
SIGW energy spectrum, which is beneficial for gravitational wave data analysis.
