  We present LZIFU (LaZy-IFU), an IDL toolkit for fitting multiple emission
lines simultaneously in integral field spectroscopy (IFS) data. LZIFU is useful
for the investigation of the dynamical, physical and chemical properties of gas
in galaxies. LZIFU has already been applied to many world-class IFS instruments
and large IFS surveys, including the Wide Field Spectrograph, the new Multi
Unit Spectroscopic Explorer (MUSE), the Calar Alto Legacy Integral Field Area
(CALIFA) survey, the Sydney-Australian-astronomical-observatory Multi-object
Integral-field spectrograph (SAMI) Galaxy Survey. Here we describe in detail
the structure of the toolkit, and how the line fluxes and flux uncertainties
are determined, including the possibility of having multiple distinct kinematic
components. We quantify the performance of LZIFU, demonstrating its accuracy
and robustness. We also show examples of applying LZIFU to CALIFA and SAMI data
to construct emission line and kinematic maps, and investigate complex, skewed
line profiles presented in IFS data. The code is made available to the
astronomy community through github. LZIFU will be further developed over time
to other IFS instruments, and to provide even more accurate line and
uncertainty estimates.
