diff --git a/docs/source/conf.py b/docs/source/conf.py
index eaa5fe2..3ba7567 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -15,19 +15,17 @@
 
 import os
 import sys
-sys.path.insert(0, os.path.abspath('../../ewstools/'))
 
+sys.path.insert(0, os.path.abspath("../../ewstools/"))
 
 
 # -- Project information -----------------------------------------------------
-project = 'ewstools'
-copyright = '2022, Thomas M Bury'
-author = 'Thomas M Bury'
+project = "ewstools"
+copyright = "2022, Thomas M Bury"
+author = "Thomas M Bury"
 
 # Semantic version number
-version = '2.0.1'
-
-
+version = "2.1.1"
 
 # -- General configuration ---------------------------------------------------
 
@@ -38,30 +36,27 @@
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = [
-    'sphinx.ext.autodoc',
-    'sphinx.ext.napoleon'
-]
+extensions = ["sphinx.ext.autodoc", "sphinx.ext.napoleon"]
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
+templates_path = ["_templates"]
 
 # The suffix(es) of source filenames.
 # You can specify multiple suffix as a list of string:
 #
-source_suffix = ['.rst', '.md']
+source_suffix = [".rst", ".md"]
 # source_suffix = {'.rst': 'restructuredtext'}
 
 
 # The master toctree document.
-master_doc = 'index'
+master_doc = "index"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = 'en'
+language = "en"
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
@@ -77,7 +72,7 @@
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'sphinx_rtd_theme'
+html_theme = "sphinx_rtd_theme"
 
 
 # Theme options are theme-specific and customize the look and feel of a theme
@@ -105,7 +100,7 @@
 # -- Options for HTMLHelp output ---------------------------------------------
 
 # Output file base name for HTML help builder.
-htmlhelp_basename = 'ewstoolsdoc'
+htmlhelp_basename = "ewstoolsdoc"
 
 
 # -- Options for LaTeX output ------------------------------------------------
@@ -114,15 +109,12 @@
     # The paper size ('letterpaper' or 'a4paper').
     #
     # 'papersize': 'letterpaper',
-
     # The font size ('10pt', '11pt' or '12pt').
     #
     # 'pointsize': '10pt',
-
     # Additional stuff for the LaTeX preamble.
     #
     # 'preamble': '',
-
     # Latex figure (float) alignment
     #
     # 'figure_align': 'htbp',
@@ -132,8 +124,7 @@
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-    (master_doc, 'ewstools.tex', 'ewstools Documentation',
-     'Thomas M Bury', 'manual'),
+    (master_doc, "ewstools.tex", "ewstools Documentation", "Thomas M Bury", "manual"),
 ]
 
 
@@ -141,10 +132,7 @@
 
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
-man_pages = [
-    (master_doc, 'ewstools', 'ewstools Documentation',
-     [author], 1)
-]
+man_pages = [(master_doc, "ewstools", "ewstools Documentation", [author], 1)]
 
 
 # -- Options for Texinfo output ----------------------------------------------
@@ -153,9 +141,15 @@
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-    (master_doc, 'ewstools', 'ewstools Documentation',
-     author, 'ewstools', 'One line description of project.',
-     'Miscellaneous'),
+    (
+        master_doc,
+        "ewstools",
+        "ewstools Documentation",
+        author,
+        "ewstools",
+        "One line description of project.",
+        "Miscellaneous",
+    ),
 ]
 
 
@@ -174,6 +168,4 @@
 # epub_uid = ''
 
 # A list of files that should not be packed into the epub file.
-epub_exclude_files = ['search.html']
-
-
+epub_exclude_files = ["search.html"]
diff --git a/ewstools/core.py b/ewstools/core.py
index 739f2f6..dc64924 100644
--- a/ewstools/core.py
+++ b/ewstools/core.py
@@ -559,10 +559,10 @@ def compute_ktau(self, tmin="earliest", tmax="latest"):
 
         # Get tmin and tmax values if using extrema
         if tmin == "earliest":
-            tmin = self.ews.dropna().index[0]
+            tmin = self.ews.dropna(how="all").index[0]
 
         if tmax == "latest":
-            tmax = self.ews.dropna().index[-1]
+            tmax = self.ews.dropna(how="all").index[-1]
 
         # Get cropped data
         df_ews = self.ews[(self.ews.index >= tmin) & (self.ews.index <= tmax)].copy()
diff --git a/requirements_dev.txt b/requirements_dev.txt
index ec8c47f..09903f0 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -13,5 +13,6 @@ plotly==5.9.0
 lmfit==1.0.3
 statsmodels==0.13.2
 scipy==1.8.1
+deprecation==2.1.0
+EntropyHub==2.0
 tensorflow==2.11.1
-deprecation==2.1.0
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 63e3e9e..8e00d30 100644
--- a/setup.py
+++ b/setup.py
@@ -3,15 +3,17 @@
 with open("README.md", "r") as fh:
     long_description = fh.read()
 
-requirements = ['pandas>=0.23.0',
-                'numpy>=1.14.0',
-                'plotly>=2.3.0',
-                'lmfit>=0.9.0', 
-                'arch>=4.4',
-                'statsmodels>=0.9.0',
-                'scipy>=1.0.1',
-                'deprecation>=2.0',
-                ]
+requirements = [
+    "pandas>=0.23.0",
+    "numpy>=1.14.0",
+    "plotly>=2.3.0",
+    "lmfit>=0.9.0",
+    "arch>=4.4",
+    "statsmodels>=0.9.0",
+    "scipy>=1.0.1",
+    "deprecation>=2.0",
+    "entropyhub>=2.0",
+]
 
 setuptools.setup(
     name="ewstools",
@@ -30,4 +32,4 @@
         "License :: OSI Approved :: MIT License",
         "Operating System :: OS Independent",
     ],
-)
\ No newline at end of file
+)