octave -> gnuplot error: shared library missing

Question

Recently, I upgraded y octave to 3.6.2, but now I cannot plot a contour with [c, h] = contourf(x,y,z,[0:0.25:3]). The following error shows that gnuplot cannot load a shared library called libreadline.so.4

This file doesn't exists in my /var/lib/ directory. Any idea how to fix this problem:

error: get: unknown axes property 
error: called from:
error:   /usr/share/octave/3.6.2/m/plot/colorbar.m at line 139, column 9
error:   /green/s61/mirjalil/MemPMF/acem-acem/forward/loadDataPMF.m at line 24, column 1
gnuplot: error while loading shared libraries: libreadline.so.4: cannot open shared object file: No such file or directory
gnuplot: error while loading shared libraries: libreadline.so.4: cannot open shared object file: No such file or directory
warning: broken pipe -- some output may be lost