Merge branch 'main' into never_copy

1 files changed, 5 insertions, 4 deletions

diff --git a/numpy/polynomial/polynomial.py b/numpy/polynomial/polynomial.py
index 940eed5e3..d8a032068 100644
--- a/numpy/polynomial/polynomial.py
+++ b/numpy/polynomial/polynomial.py
@@ -1252,10 +1252,11 @@ def polyfit(x, y, deg, rcond=None, full=False, w=None):
         diagnostic information from the singular value decomposition (used
         to solve the fit's matrix equation) is also returned.
     w : array_like, shape (`M`,), optional
-        Weights. If not None, the contribution of each point
-        ``(x[i],y[i])`` to the fit is weighted by ``w[i]``. Ideally the
-        weights are chosen so that the errors of the products ``w[i]*y[i]``
-        all have the same variance.  The default value is None.
+        Weights. If not None, the weight ``w[i]`` applies to the unsquared
+        residual ``y[i] - y_hat[i]`` at ``x[i]``. Ideally the weights are
+        chosen so that the errors of the products ``w[i]*y[i]`` all have the
+        same variance.  When using inverse-variance weighting, use
+        ``w[i] = 1/sigma(y[i])``.  The default value is None.
 
         .. versionadded:: 1.5.0