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Message: [QUOTE="mostafa.elhoushi, post: 4185416, member: 71791"] Dear All, This is the first time I post a question here in Velocity Reviews. I hope that in the future I can get more experience so that I may help answering other people's questions. I am developing a VHDL application dealing with complex numbers - and I decided to develop complex numbers using fixed point representation (using IEEE fixed_pkg): [CODE]use ieee.fixed_float_types.all; use ieee.fixed_pkg.all; .... type complex_fixed is record RE : sfixed (1 downto -10); IM : sfixed (1 downto -10); end record;[/CODE] Using this package, we can represent y=6.5 by: 1- Defining [CODE]signal y : sfixed (4 downto –5);[/CODE] which means that y has 4 binary digits before the decimal point and 5 binary digits after the decimal point. then we use either: [CODE]y <= "0011010000"; -- y = 6.5 = “00110.10000”[/CODE] OR [CODE]y <= to_sfixed(6.5);[/CODE] For more details search Google for: "Fixed point package user’s guide" Therefore I have defined the following function to ease the definition of complex numbers: [CODE]function to_cplxfixed (RE, IM: real) return complex_fixed; .... function to_cplxfixed (RE, IM: real) return complex_fixed is begin return (to_sfixed(RE, -1, 10), to_sfixed(IM, -1, 10)); end function;[/CODE] Therefore a complex number such as alpha = 1 + 0i can be represented as: [CODE]alpha: complex_fixed := to_cplxfixed((1.0, 0.0));[/CODE] Within my application, I want to deal with a matrix of complex numbers: [CODE]type cmplx_matrix is array (natural range<>, natural range<>) of complex_fixed;[/CODE] The problem I am asking for is this: When I define the following matrix: [CODE]constant I: cmplx_matrix(0 to 1, 0 to 1) := ((to_cplxfixed((1.0,0.0)), to_cplxfixed((0.0,0.0))), (to_cplxfixed((0.0,0.0)), to_cplxfixed((1.0,0.0))) );[/CODE] It passes by compilation stage in ModelSim (vcom), however an error appears to me in vsim: [CODE]# ** Fatal: (vsim-3420) Array lengths do not match. Left is 12 (1 downto -10). Right is 0 (0 downto 1 (null array)). # Time: 0 ns Iteration: 0 Region: /quantum_systems File: COMPLEX_FIXED.vhd Line: 27 # FATAL ERROR while loading design[/CODE] i.e. When it deals with I cmplx_matrix assignment, it considers the length of one dimension of the matrix being 0 to 1, and tries to equate it to the length of the result of s_fixed function. What can the solution be? [/QUOTE]

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