curandGenerateLogNormal(..) generates just a normal distribution with MTGP32 generator

Dear NVidia,

I use ManagedCuda wrapper for C# with NVidia SDK v5.5; driver 327.23 on GTX 570.
I have found a strange “feature” that device function curandGenerateLogNormal(…) when used with Mersenne Twister generator CURAND_RNG_PSEUDO_MTGP32 (141) behaves differently than all other generators - it produces Normal not Lognormal distribution. Host function using MTGP32 generator behaves as is expected.

Has anyone observed similar behavior?

I would suggest filing a bug report via the bug reporting form linked from the registered developer website. Please attach a self-contained repro app. Thank you for your help.

Below is the way to reproduce the problem quickest in C++.

Please copy the example code from NVidia’s CURAND_library.pdf section 2.5 (SDK5.5) and insert it into NVidia CUDA 5.5 project template in Visual Studio 2010 - with minor tweaks it compiles pretty quick.

Example program was modified to produce LogNormal instead of Uniform distribution {mean=0, stddev=0.5, 100000 samples} with two different generators. After copying the data to CPU from GPU, one should create a histogram in the interval of 0 to 10 with the step of 0.01.

One can then observe (either using printout or debugger) that MTGP32 produces monotonically decreasing array of numbers (0-centered normal distribution) and all other generators produce a rising then decreasing set of values as is expected i.e. a log-normal distribution.

Can send the code on request. (-:

If this is indeed a feature, not a bug, would somebody kindly explain it, please.

Below are the steps to access the bug reporting form linked from the registered developer website. If you are not a registered developer yet, it’s easy to sign up; usually applications are approved within one business day. You can attach files with repro code to the bug report. Thanks!

(1) Go to https://developer.nvidia.com/registered-developer-programs
(2) Click on “Log In” link in upper right-hand corner
(3) Log in with user name & password
(4) Hover over your user name in the upper right corner and select “My Account” from drop-down menu
(5) Click on the green link “CUDA/GPU Computing Registered Developer Program”
(6) Under the heading “Reporting an Issue”, click on green link “The Submit a Bug Form”