DOC: describe idwt2 behavior for coefficients set to None.

pywt/_multidim.py

@@ -83,7 +83,8 @@ def idwt2(coeffs, wavelet, mode='symmetric', axes=(-2, -1)):
     ----------
     coeffs : tuple
         (cA, (cH, cV, cD)) A tuple with approximation coefficients and three
-        details coefficients 2D arrays like from `dwt2()`
+        details coefficients 2D arrays like from `dwt2()`.  If any of these
+        components are set to ``None``, it will be treated as zeros.
     wavelet : Wavelet object or name string, or 2-tuple of wavelets
         Wavelet to use.  This can also be a tuple containing a wavelet to
         apply along each axis in ``axes``.
@@ -220,8 +221,8 @@ def idwtn(coeffs, wavelet, mode='symmetric', axes=None):
     Parameters
     ----------
     coeffs: dict
-        Dictionary as in output of `dwtn`. Missing or None items
-        will be treated as zeroes.
+        Dictionary as in output of ``dwtn``. Missing or ``None`` items
+        will be treated as zeros.
     wavelet : Wavelet object or name string, or tuple of wavelets
         Wavelet to use.  This can also be a tuple containing a wavelet to
         apply along each axis in ``axes``.