Skip to content

Testing the AlmaLinux9 Container with Simple Python and C++ Code

To ensure that your AlmaLinux9 container works correctly, we will test it with simple Python and C++ scripts.

Small Assignment

Suppose you have:

  • \( a = 3 \): a real-valued scalar
  • \( x = (1,1,1,\dots,1) \): a real-valued vector of dimension \(N = 20\)
  • \( y = (4,4,4,\dots,4) \): another real-valued vector of dimension \(N = 20\)

Write a program that calculates \( z = a \cdot x + y \) and prints its values to a text file.

Python code

Find the Python code in GitHub here.

scalar_prod_python.py
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
import os
import numpy as np

# Define the output file
OUTPUT_DIR = "output"
OUTPUT_FILE = "out_python.txt"
path_to_output = os.path.join(OUTPUT_DIR, OUTPUT_FILE)

# Define the input variables
a = 3
x = np.full(20, 1)
y = np.full(20, 4)

# Calculate the result z = a*x + y
z = a * x + y # z is a vector of dimension N = 20 with all elements equal to 7

# Write the result to a text file
with open(path_to_output, "w") as f:
    f.write("z = " + str(z))

Running the Python script

  1. Make sure your conda environment is activated (if you’re using Miniconda):

    conda activate python_env

  2. Install NumPy (if not already installed):

    pip install numpy

  3. Run the Python script:

    python scalar_prod_python.py

  4. Check the output file out_python.txt in the output directory.

    cat output/out_python.txt

C++ code

Find the C++ code in GitHub here.

scalar_prod_cpp.cpp
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
#include <iostream>
#include <fstream>
#include <vector>
#include <string>

const std::string OUTPUT_DIR = "output";
const std::string OUTPUT_FILE = OUTPUT_DIR + "/output_cpp.txt";

int main() {
    // Define the input values
    double a = 3;
    std::vector<double> x(20, 1.0);
    std::vector<double> y(20, 4.0);

    // Calculate z = a*x + y
    std::vector<double> z(20);
    for (int i = 0; i < 20; i++) {
        z[i] = a * x[i] + y[i];
    }

    // Write the result to a text file
    std::ofstream ofs(OUTPUT_FILE);
    if (!ofs) {
        std::cerr << "Error: Unable to open the output file\n";
        return 1;
    }
    for (double val : z) {
        ofs << val << std::endl;
    }
    ofs.close();

    return 0;
}

Compiling and running the C++ program

  1. Compile the C++ code:

    g++ -o scalar_prod_cpp scalar_prod_cpp.cpp

  2. Run the executable:

    ./scalar_prod_cpp

  3. Check the output file output_cpp.txt in the output directory:

    cat output/output_cpp.txt

Tip

If you want to store these files (both Python and C++ scripts) on your host machine permanently, place them in the shared directory you mounted (e.g., /workspace) so they persist after the container stops.