Division Problem

It might be because you divided an integer by an integer. Here is the code I used which generated 4.554600 for v_real:

module test;
  integer v_int;
  real v_real;

  initial begin
    v_int = 45546;
    v_real = v_int/10000.0;
    $display("%f", v_real);
  end
endmodule

Tim

Hello Tim,

Thanks a lot for your answer. With the integer divided by an integer you are completly right. Unfortunately I forgot in my example the $itor systme task I'm using.

The thing is, that I have a discrepance between the $display-output in the console and the waveform-output. Looks like the $display is rounding the result to 6 digits after the point and not prinitng the value which the simulator is handling. Even when I hard assign the value to v_real = 4.5546 I get a discrepance, due to the reason that a real "real-value" doesn't exist. My question is if I can tell the simulator only to have a accuracy of 4 digits after the point. I tried to convert the real-value to bits and to cut of some of the last bits. But this is not really working.

Regards,
martin

I could not see the discrepancy you had. 

DivisionWave.JPG

Here is something using SystemVerilog string function that might help you with keeping the precision to 4 places:

module test;
  integer v_int;
  real v_real, v4_real;
  string v_string;

  initial begin
    v_int = 455461;
    v_real = v_int/100000.0;
    $display("%f", v_real);
    #10 ;
    v_string.realtoa(v_real);
    $display("%f  %s", v_real, v_string);
    #10 ;
    v_string = v_string.substr(0,v_string.len()-2);
    $display("%f  %s", v_real, v_string);
    #10 ;
    v4_real = v_string.atoreal();
    $display("%f  %f", v_real, v4_real);
    #10 ;
    $finish();
  end
endmodule

 

Tim

Hi Tim,

if you move the cursor above the value on the left hand side, you can see the discrepance. Maybe I'm wrong but I think this is the most accurate value the simulator is able to use. Due to the accuracy of a floating point number.

Anyway, the example you posted is helping me with my problem and working fine. Thanks you very much, it really helps me a lot.

Regards,
martin