Concatenate arrays with different sizes in Matlab

[catmat]=padconcatenation(a,b,c)
concatenates arrays with different sizes and pads with NaN.
a and b are two arrays (one or two-dimensional) to be concatenated, c must be 1 for
vertical concatenation ([a;b]) and 2 for horizontal concatenation ([a b])

a=rand(3,4)
b=rand(5,2)
a =

0.8423 0.8809 0.7773 0.3531
0.2230 0.9365 0.1575 0.3072
0.4320 0.4889 0.1650 0.9846
b =

0.6506 0.8854
0.8269 0.0527
0.4742 0.3516
0.4826 0.2625
0.6184 0.5161

PADab=padconcatenation(a,b,1)
PADab =

0.8423 0.8809 0.7773 0.3531
0.2230 0.9365 0.1575 0.3072
0.4320 0.4889 0.1650 0.9846
0.6506 0.8854 NaN NaN
0.8269 0.0527 NaN NaN
0.4742 0.3516 NaN NaN
0.4826 0.2625 NaN NaN
0.6184 0.5161 NaN NaN

PADab=padconcatenation(a,b,2)

PADab =

0.8423 0.8809 0.7773 0.3531 0.6506 0.8854
0.2230 0.9365 0.1575 0.3072 0.8269 0.0527
0.4320 0.4889 0.1650 0.9846 0.4742 0.3516
NaN NaN NaN NaN 0.4826 0.2625
NaN NaN NaN NaN 0.6184 0.5161