On Mar 4, 12:10 pm, FPGA <FPGA.unkn...@gmail.com> wrote:
> On Mar 4, 10:45 am, Tricky <Trickyh...@gmail.com> wrote:
>
>
>
> > On Mar 4, 3:23 pm, FPGA <FPGA.unkn...@gmail.com> wrote:
>
> > > On Mar 4, 9:12 am, Tricky <Trickyh...@gmail.com> wrote:
>
> > > > On Mar 4, 2:00 pm, FPGA <FPGA.unkn...@gmail.com> wrote:
>
> > > > > On Mar 4, 4:26 am, Tricky <Trickyh...@gmail.com> wrote:
>
> > > > > > On Mar 3, 9:15 pm, FPGA <FPGA.unkn...@gmail.com> wrote:
>
> > > > > > > I have written a process to generate random numbers using UNIFORM. I
> > > > > > > was trying to check the results using "rand" in matlab. How do i
> > > > > > > initialise the seed values of both these functions to the same value.
> > > > > > > I see that the random numbers generated by UNIFORM are different
> > > > > > > compared to rand when the seed values are left uninitialised.
> > > > > > > What do I need to change so that I get same output from both programs.
>
> > > > > > > Thanks
>
> > > > > > Uninitilised positives (the seeds in this case) will take a value of 1
> > > > > > when they are put into the uniform function. Unitialised types when
> > > > > > used will take type'low as their value
>
> > > > > > positive'low = 1
> > > > > > std_logic'low = 'u'
> > > > > > etc.
>
> > > > > > so both of your first calls to uniform are seeding it with two 1s.
>
> > > > > > I dont know how the seeding works in matlab. It may not even use
> > > > > > positives, but the entire integer range. it is common in C to seed the
> > > > > > random number generator with the system time. Does matlab do something
> > > > > > similar? The C random function only has 1 seed, whereas uniform takes
> > > > > > 2.
>
> > > > > I am not sure how the rand function in MATLAB works. I tried to search
> > > > > if the code of the function was described anywhere but couldnt find.
> > > > > I dont know if we can get MATLAB to generate results as UNIFORM does.
> > > > > As you said, uniform has 2 seeds while rand has 1.
> > > > > If anyone has an idea on how this can be done, please post your
> > > > > comment.
>
> > > > Why not generate a file containing all the stimulus for the vhdl and
> > > > matlab model in one or the other, instead of trying to recreate the
> > > > random sequence?- Hide quoted text -
>
> > > > - Show quoted text -
>
> > > The goal is to check that the VHDL code generates results similar to
> > > MATLAB . I have written the outputs of both in seperate text files. I
> > > am not able to initialise the rand function to generate results
> > > similar to MATLAB and vice versa. Called MATLAB today to get some more
> > > information on how they have developed the rand function. They said
> > > that this information is not available to the public.
> > > I think one of the ways to do this would be, generating a pdf function
> > > for both cases and showing that their random distriution is similar.
>
> > > If any of you have other ideas please post them.
>
> > In that case, why are you even trying to do this? generate a file from
> > matlab that is used as the stimulus for the VHDL testbench. Then you
> > do not need to use the uniform function at all, and then you are
> > testing that the results match.- Hide quoted text -
>
> > - Show quoted text -
>
> I have to use the UNFORM function to check if it behaves in sync with
> MATLAB. I have given up on getting the same results in matlab as in
> VHDL. I am just trying to get a pdf plot of both results. No idea on
> how to do this yet.
Sounds like you have an ill-posed question here.
Mathworks won't tell you how it got it's pseudo-random stream...call
it rand(i), where rand(0)
is the seed.(In fact, you don't even know if there is a single seed or
any seed for that matter!)
You have created a pseudo-random stream fpga_rand(i), where the seed
is fpga_rand(0).
You are going to have to be satisfied with using statistical tests to
verify that
your function fpga_rand passes as many of the tests as you need, or at
least as many as the
matlab rand function passes. Look up
http://en.wikipedia.org/wiki/Diehard_tests
alan
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