# Unexpected NaN with clbas_dgemm

I am calculating a correlation matrix and am getting a weird issue. I have a 15x6 matrix R getting read into a subroutine correlation.c which calculates a 6x6 correlation matrix cor based off of the covariance matrix of R. My code looks like this

In my project's properties I set "Use Intel MKL" to "Parallel". The majority of time of my programm is matrix-vector multiplication, which is performed by mkl_ddiamv. In my task manager I always see, that ONLY ONE thread is busy by my programm process. I use Intel C++ Compiler 14.0. I try to take many different sizes of multiplicated arrays. There is no difference. I unsuccessfully tried to find some info about the reason of one-thread calculation.

# Segmentation fault with complex ScaLAPACK

Hello,

I'm trying to understand why the following simple program is segfaulting. When I'm using double instead of std::complex<double>, everything runs smoothly.

Thanks.

# mkl poisson solver with periodic and dirichlet boundary condition

Hello Sir,

I am trying to solve electrostatic Poisson's equation using Poisson MKL library 'd_Poisson_2D_c.c' but my boundary conditions are periodic (X direction) and fixed in Y direction. How shall i incorporate periodic condition in the X direction ?

I tried in this way but i donot think it is correct,

for( iy = 0; iy <= ny; iy++){

bd_ax[iy] = bd_bx[iy];

}

and  applied BCtype='PPDD' .

Thanks

# Pazzled with pdpotrf arguments

Recently I did a Cholesky decomposition with dpotrf(). My goal is to do that in a distributed environment, so I need to use pdpotrf(). However, I can not understand what values should ia, ja and desca. Can anyone please explain, since I did not find a C example about that?

I just installed Parallel Studio and need to make use of the C compiler, Fortran compiler, and math kernel library. After installing, I add source /opt/intel/bin/compilervars.sh intel64 and source /opt/intel/mkl/bin/mklvars.sh intel64 to my bashrc file (I'm running Fedora linux). When I go to check that everything has correctly added to my path I run "which ifort" and "which icc" and see the location of the ifort and icc executables. However, this method doesn't seem to work with MKL given that I don't believe there are executables for which I could run "which <blank>".

# mkl_ddiamv example

I have some problems with using mkl_ddiamv (language C). Can anybody show me a code example of using mkl_ddiamv with initialization of all the input formal parametres? It is desirable to use the number of diagonals more than one. For example, 3-diagonals with offset=[-1 0 1] and size 5 by 5 with all elements are ones.Multiplicated vectors are ones too. In different sources the matrix in special diag format is treated as two-dimensional array or one-dimensional array with row-by-row storage.

# Complex to real IFFT using MKL

Hi ,

I need to perform an IDFT of some complex data to real in FORTRAN. I have read online a lot of how to do that with MKL but it confused me more. So I need to ask some questions on the configurations I need to make to so some a transformation.

# dpotrf arguments

With the help of this great forum and old post, I was able to finally execute my first example on Cholesky factorization. However, I have a question. I call the function like this:

```  dpotrf(
&'L',
&N, // A is NxN matrix
A,
&N,
&nInfo
);
```

Since I am planning to do a distributed factorization, I have to be sure about the arguments. What is the latter 'N' used for? My first thought was about the dimension of the output, but that's the same array, so I am confused.

# Simultaneous diagonalization of commuting matrices

Dear Intel MKL colleagues,

May I ask please to someone let me know, if there is any built-in function or easy to follow process for simultaneous diagonalization of multiple (or even two) commuting matrices in Intel MKL ?

Any help would be appreciated.

Best regards,

Younes