Numerical Data Processor in C

I need a clean, well-structured C program dedicated to data processing, specifically for numerical datasets. The application should accept a file or stream of numbers, carry out essential statistical operations—think totals, averages, minimums, maximums, and any other core metrics you recommend—and then write the results to either standard output or a separate report file.

Please use standard C (C99 or newer) and keep external libraries to an absolute minimum so that the code compiles on any POSIX-compliant system with nothing more than gcc and make. Readability matters: clear function names, sensible modularisation, and inline comments that explain the logic rather than restate it. Alongside the source, include:

• A Makefile that builds everything with a single make command
• A concise README with build/run instructions and example input/output
• Test data or a small test harness to demonstrate correctness

There’s no strict deadline—I value robustness and maintainability over a quick turnaround—so take the time you need to ensure the solution is efficient, accurate, and easy for another C developer to extend later.