  We combine photometry from the UDS, and CANDELS UDS and CANDELS GOODS-S
surveys to construct the galaxy stellar mass function probing both the low and
high mass end accurately in the redshift range 0.3<z<3. The advantages of using
a homogeneous concatenation of these datasets include meaningful measures of
environment in the UDS, due to its large area (0.88 deg^2), and the high
resolution deep imaging in CANDELS (H_160 > 26.0), affording us robust measures
of structural parameters. We construct stellar mass functions for the entire
sample as parameterised by the Schechter function, and find that there is a
decline in the values of phi and of alpha with higher redshifts, and a nearly
constant M* up to z~3. We divide the galaxy stellar mass function by colour,
structure, and environment and explore the links between environmental
over-density, morphology, and the quenching of star formation. We find that a
double Schechter function describes galaxies with high Sersic index (n>2.5),
similar to galaxies which are red or passive. The low-mass end of the n>2.5
stellar mass function is dominated by blue galaxies, whereas the high-mass end
is dominated by red galaxies. This hints that possible links between
morphological evolution and star formation quenching are only present in
high-mass galaxies. This is turn suggests that there are strong mass dependent
quenching mechanisms. In addition, we find that the number density of high mass
systems is elevated in dense environments, suggesting that an environmental
process is building up massive galaxies quicker in over densities than in lower
densities.
