Measuring the scalar induced gravitational waves from observations
  We measure the scalar induced gravitational waves from the cosmic microwave
background (CMB) observations and the gravitational wave observations. In the
$\Lambda$CDM+$r$ model, we constrain the cosmological parameters within the
evolution of the scalar induced gravitational waves by the additional scalar
power spectrum. The two special cases called narrow power spectrum and wide
power spectrum have influence on the cosmological parameters, especially the
combinations of Planck18+BAO+BK15+LISA. We also compare these numerical results
from four datasets within LIGO, LISA, IPTA and FAST projects, respectively. The
constraints from FAST have a significant impact on tensor-to-scalar ratio.
