Nazar R. wrote:
> Can eny one help me?
1.) Read the manual of the edit box:

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Reply

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Rules — please read before posting

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Formatting options

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   [vhdl]VHDL code[/vhdl]

2.) Use indention and advanced formatting to get a readable code.

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if sqrt(sqrt1) mod 1.0/= 0.0 then

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   while sqrt(sqrt1+k1*p1) mod 1.0 /= 0.0 loop

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      k1<=k1+1.0;

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      exit when sqrt(sqrt1+k1*p1) mod 1.0 > 0.0;

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   end loop;

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   g1<=sqrt(sqrt1+k1*p1) mod p1;

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else

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   g1<=sqrt(sqrt1)mod p1;

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end if;

3.) What data types have the used signals?
Integer? Real?

> p1=< 28623421
What is "p1"? Is it the input parameter for the incomplete function or 
the unknown process?

> For example p1=< 28623421, sqrt1 >= p1.
What does that mean? What do you expect? What do you get instead? And 
HOW do you get that?


Simply attach the complete *.vhd file...

p1 is a input data, real character, as the sqrt1 value

it`s all the part of math expression, in this part i have problem with 
get sqrt function

Nazar R. wrote:
> it dosen`t work corectly with big data(number). For example p1=<
> 28623421, sqrt1 >= p1. Can eny one help me?
I suppose you simply have a problem with the number of significant 
digits of a real number.
See that: http://codepad.org/s4xolHhg

no you`a wrone. i know how to write real data type. this part of code 
must work with real type because sqrt function work only on this type

i have just a code problem with loop statment

Nazar R. wrote:
> this part of code must work with real type
What figures/value/nubmers have those parameters?

Or the other way: show your complete code and the corresponding test 
bench. Otherwise we will not get a point here...  :-/

this is my diagram

value, parameters i wrote uper this page. this p1.. you need just put 
into the program

> while sqrt(sqrt1+k1*p1) mod 1.0 /= 0.0
Thats the problem: never ever check real values for equality...

why? if you try to write this sentens into the paper and do some math 
you have tru answer. in this line i do some chek, if sqrt1... after do 
mod operation exit the 0 state

but it works for real type isn`t?

out of the mist wrote:
> mod is defined for integers but not for real.
Only in C...

But look at this:
http://codepad.org/1q85mdCr

A float value nearly never is something like .0000000!
Its more something like .00001 or .999999
Nearly never the result of that operation will be 0.0

Have a close look for the math_real package:
https://standards.ieee.org/downloads/1076/1076.2-1996/math_real.vhdl

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    function "MOD" (X, Y: in REAL ) return REAL;

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        -- Purpose:

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        --         Returns floating point modulus of X/Y, with the same sign as

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        --         Y, and absolute value less than the absolute value of Y, and

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        --         for some INTEGER value N the result satisfies the relation

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        --         X = Y*N + MOD(X,Y)

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        -- Special values:

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        --         None

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        -- Domain:

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        --         X in REAL; Y in REAL and Y /= 0.0

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        -- Error conditions:

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        --         Error if Y = 0.0

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        -- Range:

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        --         ABS(MOD(X,Y)) < ABS(Y)

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        -- Notes:

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        --         None

thats a point to catch the number when sqrt1 have 0.0.

in my work i use real type bacause i use sqrt operators a lot of time, 
thets why i convert all of my variables to real from integer type. all 
operations in the my model give me result in some sing like that 100.0, 
152.0, 343558137.0

Martin wrote:
> mod 1.0 is almost ALWAYS unequal 0.0
Or the other way: NEVER EVER compare a float value to equality

Even if two float numbers "look" the same, they may be different:
http://codepad.org/FO8DdkGk

Nazar R. wrote:
> all operations in the my model give me result in some sing like that
> 100.0, 152.0, 343558137.0
No, they don't. Think about that, its a "problem" of how a real value is 
defined in IEEE 754.

write in the calc 123 mod 1 and you have 0 but if you input 123.5 exit 
number is cheged. f**ck i dont know how discribe you my problem

in the line sqrt(sqrt1+k1*p1) outputs may take value like 12.5, 
1427.333. thets why i wrote mod 1

i must get full number without floating data *.45

Nazar R. wrote:
> write in the calc
In which one?

> 123 mod 1
The mod function is NOT the problem here.

> i dont know how discribe you my problem
Looks alike...

Nazar R. wrote:
> all operations in the my model give me result in some sing like that
> 100.0, 152.0, 343558137.0
Where do you see this values?

For those .0 values have a look there:
http://codepad.org/SlmEEkho
You CANNOT compare a float number for equality...

do you have active-hdl?

Nazar R. wrote:
> do you have active-hdl?
Yes. Active HDL also uses the IEE 754 format. And therefore it also has 
the same restrictions...

> do you have active-hdl?
But as I already said several times: post your complete VHDL file (as 
a *.vhd or *.vhdl file pls!) and the test bench so everybody else can 
test your specific problem on his simulator. You can attach several 
files to one post...

sorry i attach only bench file before

> use IEEE.std_logic_unsigned.all;
> use IEEE.std_logic_signed.all;
> use ieee.numeric_std.all;
> use IEEE.std_logic_arith.all;
Ouch, ouch, ouch, ouch...

EITHER use the use numeric_std (best and preferred choice)
OR use those two: std_logic_signed and std_logic_arith
OR use those two: std_logic_unsigned and std_logic_arith
BUT do NOT use all of them together. Otherwise you have multiple type 
definitions and therfore sometimes very weird behaviour...

Nazar R. wrote:
> sorry i attach only bench file before
A test bench usually is a *.vhd module WITHOUT ports in the entity. I 
will have a look at that tomorrow, now I'm away for the night... ;-)

This will never happen:
> exit when sqrt(sqrt1+k1*p1) mod 1.0 > 1.0;
Something mod 1.0 is always less then 1.0
Therefore this "exit" is useless and obsolete.

I took your code and transferred it into a little bit more handy test 
bench. My conclusion: I can se no sense in those calculations. With the 
values in the code I have 1.5 million loop iterations...

So the big question is:
What should this code do? Whats the origin of this code? Whats its 
purpose?

You may also try this in your simulator:

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library IEEE;

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use IEEE.STD_LOGIC_1164.ALL;

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use IEEE.math_real.ALL;

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entity tb_real_test is

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end tb_real_test;

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architecture Behave of tb_real_test is

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signal a : real := 23456789.0;

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begin

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  process (a)

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  variable j : real;

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  begin

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     j := sqrt(12100.0);

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     if a=a*j/111.0 then report "a) equal!";

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     else                report "a) different!";

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     end if;

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     if a mod 1.0 = 0.0 then report "1. remainder is zero!";      end if;

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     if a*j/111.0 mod 1.0 = 0.0 then report "2. remainder is zero!";  end if;

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     j := 111.1;

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     if a=a*j/111.1 then report "b) equal!";

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     else                report "b) different!";

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     end if;

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     if a*j/111.1 mod 1.0 = 0.0 then report "3. remainder is zero!";  end if;

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     j:=a*j/111.1 mod 1.0;

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     report "Should be .0 --> " & real'image(j); 

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  end process;

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end;

Think about the results...

So, let's again. I am engaged in developing advanced algorithm Rabin 
among Atstsdf. Part of my code should find the square root of a number. 
Do I have to check this number due to the fact that this number must 
then be multiplied by the transaction module and there should get an 
integer. small numbers I come out all right, here's an example I attach 
a file, it should just run. I ask if large numbers fixate the process of 
calculating and never stops

Nazar R. wrote:
> I am engaged in developing advanced algorithm Rabin among Atstsdf.
Must this code be implemented on a FPGA in future? Then forget about 
real...

> here's an example I attach a file, it should just run.
And what should happen?

> here's an example I attach a file, it should just run.
Attach a second one that doesn't "run". And tell how you can see that...

> exit when sqrt(sqrt1+k1*p1) mod 1.0 < 1.0;
Something mod 1.0 is ALWAYS less then 1.0, so here the loop will ALWAYS 
be terminated...

Did you read the post https://embdev.net/topic/384548#4390186
Did you understand it?

Let me say it this way: I've shown you some major design flaws and you 
ignored all of that hints. I've also shown you a way to set up a 
little bit more "talky" test bench and you dig further on with your 
code. What do you expect as "help"?