title: The difference between C++ (LAPACK, sgels) and Python (Numpy, lstsq) results
body: <p>I am comparing the numerical results of C++ and Python computations. In C++, I make use of LAPACK's sgels function to compute the coefficients of a linear regression problem. In Python, I use Numpy's linalg.lstsq function for a similar task.</p>
  
  <p>What is the mathematical difference between the methods used by sgels and linalg.lstsq?</p>
  
  <p>What is the expected error (e.g. 6 significant digits) when comparing the results (i.e. the regression coefficients) numerically?</p>
  
  <p>FYI: I am by no means a C++ or Python expert, which makes it difficult to understand what is going on inside the functions.</p>