Store complex decimal values as 2D array in a rom in verilog

For a 72x300 matrix you could use a rom with 128 by 512 addresses (64k). The Upper 7 bit is your first axis, the lower 9 addresses is your second axis in this case.

Depending on the data width this will be a big RAM, at least for a FPGA onchip Memory.

Assuming that your double value has 64bit you need 512kByte.

The 7 by 7 matrix needs 64 adresses with 128bit each:

module array (
		input   x_i,
		input   y_i,
		output  re_o,
		output  im_o
	);
	reg  array;
	initial
	begin
		array = {64'h00000000deadbeef, 64'h00000000affedead};
		array = {64'h0000000000000000, 64'h0000000011111111};
		array = {64'h0000000011111111, 64'h0000000022221111};
	end
	assign re_o = array;
	assign im_o = array;
	
endmodule

Though i don't know your exact requirements i would recommend to use the Altera altsyncram with a initialization .mif File. And a big enough FPGA.