fix pinv (#2110)

mlx/linalg.cpp

@@ -379,7 +379,12 @@ array pinv(const array& a, StreamOrDevice s /* = {} */) {
   // Prepare S
   S = expand_dims(S, -2, s);
 
-  return matmul(divide(V, S, s), U);
+  auto rcond = 10. * std::max(m, n) * finfo(a.dtype()).eps;
+  auto cutoff = multiply(array(rcond, a.dtype()), max(S, -1, true, s), s);
+  auto rS =
+      where(greater(S, cutoff, s), reciprocal(S, s), array(0.0f, a.dtype()), s);
+
+  return matmul(multiply(V, rS, s), U, s);
 }
 
 array cholesky_inv(