Scientific Computing

CMake can create relocatable installer or archive packages with CPack. CPack creates an archive or installer from a CMake project. C and C++ programs generally use header files (.h or .hpp) that must be part of an installed package. Fortran programs likewise use module files (.mod) that must be installed.

A basic structure for a CMake project that can create a CMake config-file package is shown in cmake-package-install. The boilerplate code under cmake/ directory is only slightly modified between projects. For example, see h5fortran for more advanced example in cmake/install.cmake and cmake/config.cmake.in.

On Windows, Anaconda Python can install GCC libraries such as libstdc++ and libgfortran et al under miniconda3/Library/mingw-w64/bin. This path is put by default by fresh Anaconda installation on Path by “conda activate”, but no files are installed there until certain packages are installed. These libraries are for a particular GCC version, and are not necessarily ABI compatible with the GCC version on the system perhaps from MSYS2.

This problem can manifest as Windows error code 139 when running other executables that need say libstdc++ but Anaconda’s path is overriding the desired GCC lower on Path.

The solution to this problem could be either:

• uninstall the conda Python package that installed those libraries
• rename the Library/mingw-w64/bin e.g. to bin-backup and see if the needed Python packages still work

We generally recommend using Ninja with CMake, especially for large projects. Ninja speeds up rebuild times significantly and avoids erratic problems with slower GNU Make. CMake also has the Ninja Multi-Config generator

cmake -G "Ninja Multi-Config"

that allows building multiple build configuration types e.g. Debug, Release without CMake regenerating build*.ninja files for each build type with totally distinct build root directories.

Ninja Multi-Config generator options may be used transparently with older CMake and different generators. The default CMake generator can be set with environment variable:

CMAKE_GENERATOR="Ninja Multi-Config"

To make the default multi-config build “Release” while making Debug config also available, set environment variable CMAKE_CONFIGURATION_TYPES:

CMAKE_CONFIGURATION_TYPES="Release;RelWithDebInfo;Debug"

Because Release is listed first, the default build type is Release. With those settings, one can quickly build Debug and Release and test like:

cmake -B build

# Release default per above settings
cmake --build build

ctest --test-dir build -C Release

Then quickly build and test Debug without regenerating CMake/Ninja build files by:

cmake --build build --config Debug

ctest --test-dir build -C Debug

In general, computers using vPro remote access should not be directly exposed to the Internet. The computer’s software firewall doesn’t block vPro ports, which exist outside of the operating system. An external firewall is necessary to protect vPro remote access.

Remote firewall connections to Intel vPro machines can be made via SSH port forward to use Intel AMT KVM. Don’t open Intel AMT vPro ports ports to the public Internet. These ports are the minimum that we’ve observed are necessary to use Intel AMT for remote control, including remote power cycling.

To diagnose vPro remotely, first connect with the ports above forwarded to the laptop, then browse to https://localhost:16993. Connect using MeshCommander as VNC is no longer supported.

Reference: Intel AMT network ports

Patching files with GNU Patch has been a common task for decades. Due to technical issues with potential patch library implementation, CMake does not include a native patch function. We use CMake to detect if “patch” is available, which it virtually always is on Unix-like systems. For Windows, we use MSYS2 or WSL.

CMake Patch file repository example uses standard GNU Patch files across operating systems. We put the patched file into the binary directory to avoid ambiguity. The file patching occurs only if the source file changes using canonical CMake approach.

With slight modification, this patching can occur on files obtained via CMake FetchContent, header files, or other resources.

Fix Python on Windows:

error Microsoft Visual C++ 14.0 is required

by installing Microsoft Build Tools for Visual Studio.

Select: Workloads → Desktop development with C++, then for Individual Components, select only:

• Windows SDK
• C++ x64/x86 build tools

The build tools allow using MSVC “cl.exe” C / C++ compiler from the command line.

Visual Studio changed the Build Tools from being C++ specific in late 2017. Thus newer Visual Studio versions work in place of older versions.

Windows Python needs Visual C++ libraries installed via the SDK to build code, such as via setuptools.extension.Extension or numpy.distutils.core.Extension. For example, building f2py modules in Windows with Python requires Visual C++ SDK as installed above. On Unix-like operating systems, the C++ libraries are installed with the compiler.

Python / Visual Studio build matrix

Matlab offers embedded system support including most Raspberry Pi models.

A downside of this prototyping method is reliance on an opaque proprietary toolchain. If the prototype has a corner case Mathworks didn’t anticipate the project may have to be recoded in another language such as Python that runs directly on the embedded computer.

Another alternative is running the Matlab script directly on the embedded system using GNU Octave. We have achieved 30+ fps batch processing on video motion streams on the Raspberry Pi Zero with GNU Octave. Popular Raspberry Pi operating systems can easily install a recent GNU Octave.

apt install --no-install-recommends octave

First try Octave on a laptop to verify the particular Matlab script works with Octave. If the script doesn’t work with Octave and it seems too difficult to do so, consider transitioning to Python.

Most programming languages have a built-in random number generator. Using an a priori random seed can be useful in testing simulations using randomness. In simulations with non-linear growth, small differences at the beginning of the simulations can result in significantly different time evolution of the outputs. To help test such simulations as compared against known-good reference data, it can be useful to set a known random seed to see that expected outputs result.

In Python Numpy, the random seed can be set:

import numpy.random

r = numpy.random.default_rng(seed=0)

x = r.standard_normal(3)

Observe that “x” will always be

[ 0.12573022 -0.13210486 0.64042265]

using different seed values result in a different set of repeatable pseudorandom numbers.

NOTE: the default RNG is not guaranteed to be stable over Numpy releases. The user may wish to specify a specific RNG like:

r = numpy.random.Generator(numpy.random.PCG64(seed=0))

The Anker Soundcore Life P2 has excellent sound quality. For use with more than one device, consider instead earbuds that have multipoint Bluetooth (the Soundcore Life P2 earbuds do not have multipoint). The FCC ID is “2AOKB-A3919RT”.

In general for Bluetooth earbuds of any brand, it’s best to carry the charging container with you to protect and charge the earbuds when not in use. You may need to manually select “headset” or “stereo” mode in your operating system. Windows for example allows per-app defaults, or switch by clicking on Windows toolbar speaker icon.

The “pros” or upsides of these earbuds:

• Excellent stereo sound quality including aptX
• Works well with single earbud (left or right) and auto-enables stereo if 2nd earbud turned on (or mono if 2nd earbud turned off).
• four microphones (two per ear) give excellent quality on two-way audio e.g. videoconferencing
• holds in ear well with several earmold sizes–comfortable used several hours per day
• USB-C charging jack on container, which fits well in pocket

The “cons” or downsides of these earbuds include negative characteristics that are serious enough to consider buying a different model earbud.

• no multipoint Bluetooth–switching devices effectively requires repairing each time.
• flashing status light annoyingly bright, particularly at night. They are like a “mug me” beacon if walking outside at night.

Re-pair both earbuds

Sometimes the earbuds lose sync with each other, so that they only function individually not as a stereo pair. The procedure for resetting / recovering stereo sync is from Soundcore support:

• “Forget” the pairing with both Soundcore earbuds on your device
• Place the earbuds into the charging case and ensure they are being charged (white light steady)
• Press and hold the button on both earbuds for 3 seconds. The LED indicators will flash red 3 times and then turn white briefly. Release the buttons when the light turns white.

Now wait for about a minute.

• Take both earbuds out of the charging case, and lay them where you can see each earbuds’ light.
• after a few seconds, the white light on one (usually right) earbud will flash quickly, which means it enters pairing mode.
• On the phone, add device named “Soundcore” or “Soundcore-L” on the Bluetooth list. The white light will flash slowly, which means it paired successfully.
• A few seconds later, there will pop out a screen with “Bluetooth Pairing Request”, just click “Pair” (this step is very important)

In the bluetooth pairing list the Soundcore is displayed as “connected”, and the Soundcore-L is displayed as “not connected”. In fact, the earbuds are normally TWS paired to work

The MSYS2 GitHub Action v2.5.0 updated the path to MSYS, affecting workflows using MSYS2.

The new path is used like:

- name: Put MSYS2_MinGW64 on PATH
  # there is not yet an environment variable for this path from msys2/setup-msys2
  run: echo "${{ runner.temp }}/msys64/ucrt64/bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append