Quartus does not support the module IO were defined as real or user defining ?

for example:

ENTITY interpolation_filter IS

PORT( clk : IN std_logic;

clk_enable : IN std_logic;

reset : IN std_logic;

filter_in : IN real; -- double

filter_out : OUT real -- double

);

END interpolation_filter;

Compiling eror:

Error (10414): VHDL Unsupported Feature error at interpolation_filter.vhd(39): cannot synthesize non-constant real objects or values

Error (10414): VHDL Unsupported Feature error at interpolation_filter.vhd(40): cannot synthesize non-constant real objects or values