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Questions tagged [blas]

The Basic Linear Algebra Subprograms are a standard set of interfaces for low-level vector and matrix operations commonly used in scientific computing.

A reference implementation is available at NetLib; optimized implementations are also available for all high-performance computing architectures, for example:

The BLAS routines are divided into three levels:

  • Level 1: vector operations e.g. vector addition, dot product
  • Level 2: matrix-vector operations e.g. matrix-vector multiplication
  • Level 3: matrix-matrix operations e.g. matrix multiplication
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What is the relation between BLAS, LAPACK and ATLAS

I don't understand how BLAS, LAPACK and ATLAS are related and how I should use them together! I have been looking through all of their manuals and I have a general idea of BLAS and LAPACK and how to use them with the very few examples I find, but I…
makhlaghi
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How does BLAS get such extreme performance?

Out of curiosity I decided to benchmark my own matrix multiplication function versus the BLAS implementation... I was to say the least surprised at the result: Custom Implementation, 10 trials of 1000x1000 matrix multiplication: Took: 15.76542…
DeusAduro
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How to check BLAS/LAPACK linkage in NumPy and SciPy?

I am builing my numpy/scipy environment based on blas and lapack more or less based on this walk through. When I am done, how can I check, that my numpy/scipy functions really do use the previously built blas/lapack functionalities?
Woltan
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Why does multiprocessing use only a single core after I import numpy?

I am not sure whether this counts more as an OS issue, but I thought I would ask here in case anyone has some insight from the Python end of things. I've been trying to parallelise a CPU-heavy for loop using joblib, but I find that instead of each…
ali_m
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Benchmarking (python vs. c++ using BLAS) and (numpy)

I would like to write a program that makes extensive use of BLAS and LAPACK linear algebra functionalities. Since performance is an issue I did some benchmarking and would like know, if the approach I took is legitimate. I have, so to speak, three…
Woltan
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Is armadillo solve() thread safe?

In my code I have loop in which I construct and over determined linear system and try to solve it: #pragma omp parallel for for (int i = 0; i < n[0]+1; i++) { for (int j = 0; j < n[1]+1; j++) { for (int k = 0; k < n[2]+1; k++) { …
maxdebayser
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MatLab error: cannot open with static TLS

Since a couple of days, I constantly receive the same error while using MATLAB which happens at some point with dlopen. I am pretty new to MATLAB, and that is why I don't know what to do. Google doesn't seem to be helping me either. When I try to…
Hans Meyer
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TensorFlow: InternalError: Blas SGEMM launch failed

When I run sess.run(train_step, feed_dict={x: batch_xs, y_: batch_ys}) I get InternalError: Blas SGEMM launch failed. Here is the full error and stack trace: InternalErrorTraceback (most recent call last) in…
rafaelcosman
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Distributing Cython based extensions using LAPACK

I am writing a Python module that includes Cython extensions and uses LAPACK (and BLAS). I am open to using either clapack or lapacke, or some kind of f2c or f2py solution if necessary. What is important is that I am able to call lapack and blas…
jcrudy
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TensorFlow: Blas GEMM launch failed

When I'm trying to use TensorFlow with Keras using the gpu, I'm getting this error message: C:\Users\nicol\Anaconda3\envs\tensorflow\lib\site-packages\ipykernel\__main__.py:2: UserWarning: Update your `fit_generator` call to the Keras 2 API:…
Nicolas
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Purpose of LDA argument in BLAS dgemm?

The Fortran reference implementation documentation states: * LDA - INTEGER. * On entry, LDA specifies the first dimension of A as declared * in the calling (sub) program. When TRANSA = 'N' or 'n' then * LDA must be…
Setjmp
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Compiling numpy with OpenBLAS integration

I am trying to install numpy with OpenBLAS , however I am at loss as to how the site.cfg file needs to be written. When the installation procedure was followed the installation completed without errors, however there is performance degradation on…
Vijay
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multithreaded blas in python/numpy

I am trying to implement a large number of matrix-matrix multiplications in Python. Initially, I assumed that NumPy would use automatically my threaded BLAS libraries since I built it against those libraries. However, when I look at top or something…
Lucas
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Keras not using multiple cores

Based on the famous check_blas.py script, I wrote this one to check that theano can in fact use multiple cores: import os os.environ['MKL_NUM_THREADS'] = '8' os.environ['GOTO_NUM_THREADS'] = '8' os.environ['OMP_NUM_THREADS'] =…
Herbert
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Linking Intel's Math Kernel Library (MKL) to R on Windows

Using an alternative BLAS for R has several advantages, see e.g. https://cran.r-project.org/web/packages/gcbd/vignettes/gcbd.pdf. Microsoft R Open https://mran.revolutionanalytics.com/documents/rro/installation/#sysreq is using Intel's MKL instead…
majom
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