Use of SXT function in VHDL

[sougata_vlsi13]

Can anyone please tell what is the use of SXT function in VHDL.I have searched in the net but not able to get a clear idea about that

 

[TrickyDicky]

SXT is not a standard VHDL function. it is part of the std_logic_arith library to sign extend a std_logic vector.

But why you would want to sign extend a std_logic_vector is silly, as a std_logic_vector is not a number.