All Questions
26 questions
1
vote
1
answer
151
views
Can I multiply the real parts of two complex matrices using dgemm?
I have two complex matrices A and B, with matching shapes.
Is there a way to cleverly setup the dgemm arguments so as to get the result of the matrix multiplications of the real parts of these ...
- 491
0
votes
1
answer
54
views
BLAS dnrm2 on Scipy returns wrong value. Possible wrong flattening
I am trying to use Scipy's BLAS functions from Cython and i want to call the dnrm2 for the l2 norm on a 2D typed memoryview.
From the BLAS documentation, the dnrm2 returns the Euclidian norm of a ...
2
votes
1
answer
469
views
Maximizing the speed of Cython array operations when using typed memory views and BLAS
I'm trying to maximize the speed of my Cython 3.0 code that involves updating an array with a loop of several array operations (including matrix-vector multiplication, vector-vector addition, and ...
- 35
0
votes
0
answers
311
views
Scipy Blas/Lapack: Force use of AVX instruction set
I've written a simple cython program using scipy.linalg.cython_blas. When profiling the code, I see that the blas routines such as dgemv and dgemm are using the SSE instruction set. Given that my ...
- 99
2
votes
1
answer
213
views
Solve PSD linear system
I am trying to compute with BLAS/LAPACK the matrix $A - A B^{-1} A$ where A is symmetric and B is PSD.
What would be the smartest way to do this?
I was thinking to compute a Cholesky decomposition $B =...
- 23
0
votes
0
answers
132
views
OpenMP implementation slowed down by Lapack's DSYSV
I have written an algorithm in Cython that frequently executes Lapack and Blas routines. As the individual calls to these routines are independent of each other, I attempted to speed things up by ...
- 344
4
votes
3
answers
936
views
Link Cython-wrapped C functions against BLAS from NumPy
I want to use inside a Cython extension some C functions defined in .c files that uses BLAS subroutines, e.g.
cfile.c
double ddot(int *N, double *DX, int *INCX, double *DY, int *INCY);
double ...
- 1,279
3
votes
1
answer
1k
views
How to make cython function accept float or double array input?
Suppose I have the following (MCVE...) cython function
cimport cython
from scipy.linalg.cython_blas cimport dnrm2
cpdef double func(int n, double[:] x):
cdef int inc = 1
return dnrm2(&n, &...
- 13.2k
3
votes
2
answers
625
views
wrapping the ScaLAPACK functions in cython
I used lapack and blas library to implement matrix-inversion and multiply matrices in cython. Here is my code:
import numpy as np
cimport numpy as np
cimport cython
import ctypes
cdef extern ...
- 4,328
4
votes
2
answers
333
views
scipy BLAS routine does not overwrite input despite using overwrite_a=True
I am used to using BLAS routines in cython (from scipy.linalg.cython_blas), where the input is very often modified in place (for example, in the dger routine).
I'm trying to do the same with scipy....
- 13.2k
2
votes
0
answers
106
views
cython_blas level 1 routine orders of magnitude faster than Cython for loop
I've come across a performance difference between a call to cblas (namely daxpy: perform y += alpha * x where y and x are vectors of the same length, and alpha is a scalar) and the same operation ...
- 13.2k
2
votes
1
answer
2k
views
Using the Scipy cython_blas interface from Cython not working on vectors Mx1 1xN
This has to deal with a similar problem here: Calling BLAS / LAPACK directly using the SciPy interface and Cython but is different because I'm using the actual code in the SciPy example here ...
- 2,842
4
votes
1
answer
2k
views
Calling BLAS / LAPACK directly using the SciPy interface and Cython
There was a post on this here: https://gist.github.com/JonathanRaiman/f2ce5331750da7b2d4e9 which shows a great speed improvement by just calling the Fortran libraries (BLAS / LAPACK / Intel MKL / ...
- 2,842
2
votes
1
answer
385
views
Using Fortran NumPy operations in Cython with NOGIL, what's the Fortran library equivalent to NumPy multiply?
So I'm trying to help another SO user, and in the process I can't create a Cython program to do something simple outside of NumPy which forces me to use the GIL. So that makes using OpenMP (multicore) ...
- 2,842
2
votes
1
answer
933
views
Calling blas ddot from Cython
I'm trying to use the dot product from BLAS library using Cython, but when the compiled module is called appears the following traceback "undefined symbol: cblas_ddot". Executing the np.config.show() ...
