\begin{table}%t4
%\centering
\par
\caption{Number of stars in the D1 field for $i' < 21$ and in different
intervals of  $r'-i'$. Column 1 indicates the middle of the interval of width 0.2, 
"tot'' means the total of the 3 interval considered, that is $1.5< r'-i'<2.1$. 
Columns~2 to~17 give the model counts for each of
the tested LF while column 18 contains the observed counts. Models are described by two 
parameters: on the first line of the column heading the value of the mass of changing 
slope is indicated, the second line gives the value of~$\alpha$ (see Eq.~(\ref{imf})).
The column values include, in the first line,  the number of stars in the colour interval, 
the second line gives the difference between the data and simulated counts in number of 
sigmas, assuming that the noise is
dominated by the Poisson statistics (see text). Model with values between --3 and +3 are 
considered as acceptable in the colour bin.\label{table_lf_sigma_d1}}
\begin{tabular}{c|c|ccccc|ccccc|ccccc|c}
\hline\hline
$r'-i'$&std&.15&.15&.15&.15&.15&.20&.20&.20&.20&.20&.25&.25&.25&.25&.25&data\\
     &              & 2 & 2.5 & 3 & 3.5 & 4 & 2 & 2.5 & 3 & 3.5 & 4 & 2 & 2.5 & 3 & 3.5 & 4 &\\
\hline
1.6 &     79 &   82 &   84 &   87 &   88 &   88 &   88 &  106 &  124 &  148 &  176 &  100 &  134 &  173 &  229 &   299 &        126\\
        $\sigma$&     4.2 &     3.9 &     3.7 &     3.5 &     3.4 &     3.4 &      3.4 &     1.8 &     0.2 &    --2.0 &    --4.5 &     2.3 &    --0.7 &    --4.2 &    --9.2 &   --15.4 & \\
\hline
1.8 &     25 &   30 &   35 &   38 &   41 &   50 &   35 &   47 &   62 &   76 &  102 &   41 &   58 &   84 &  121 &   172 &        57\\
        $\sigma$&     4.2 &     3.6 &     2.9 &     2.5 &     2.1 &     0.9 &      2.9 &     1.3 &    --0.7 &    --2.5 &    --6.0 &     2.1 &    --0.1 &    --3.6 &    --8.5 &   --15.2 & \\
\hline
2.0 &     11 &   13 &   16 &   18 &   23 &   26 &   15 &   18 &   29 &   42 &   59 &   15 &   24 &   37 &   61 &    95 &        21\\
        $\sigma$&     2.2 &     1.7 &     1.1 &     0.7 &    --0.4 &    --1.1 &      1.3 &     0.7 &    --1.7 &    --4.6 &    --8.3 &     1.3 &    --0.7 &    --3.5 &    --8.7 &   --16.1 & \\
\hline
tot&     115 &  125 &  135 &  142 &  151 &  165 &  138 &  171 &  215 &  266 &  337 &  157 &  216 &  294 &  411 &   566 &        204\\
        $\sigma$&     6.2 &     5.5 &     4.8 &     4.3 &     3.7 &     2.7 &      4.6 &     2.3 &    --0.8 &    --4.3 &    --9.3 &     3.3 &    --0.8 &    --6.3 &   --14.5 &   --25.3 & \\
\hline
\end{tabular}
\end{table}