Apply suggestions from code review

Co-authored-by: Echedey Luis <80125792+echedey-ls@users.noreply.github.com>

Author: cwhanse

pvlib/ivtools/utils.py

@@ -593,8 +593,8 @@ def _lambertw_pvlib(x):
     # for small x, solve 0 = g(w) = w * exp(w) - x using Halley's method
     if np.any(small):
         z = localx[small]
-        temp = np.log(localx[small] + 1)
-        g = temp - np.log(temp + 1)
+        temp = np.log1p(localx[small])
+        g = temp - np.log1p(temp)
         for _ in range(0, 3):
             expg = np.exp(g)
             g_expg_z = g*expg - z

tests/ivtools/test_utils.py

@@ -185,10 +185,10 @@ def test_lambertw_pvlib():
     result = _lambertw_pvlib(test_x)
     assert np.allclose(result, expected, rtol=1e-14)
     # with float input
-    for x, k in zip([1.e-10, 1.e+10], [1, 5]):
+    for x, k in zip(test_x[[1, 5]], expected[[1, 5]]):
         result = _lambertw_pvlib(x)
         assert np.isclose(result, expected[k])
     # with 1d array
-    for x, k in zip([1.e-10, 1.e+10], [1, 5]):
+    for x, k in zip(test_x[[1, 5]], expected[[1, 5]]):
         result = _lambertw_pvlib(np.array([x]))
         assert np.isclose(result, expected[k])