diff --git a/python/_cosmomath.pyx b/python/_cosmomath.pyx
new file mode 100644
index 0000000..4b2b21f
--- /dev/null
+++ b/python/_cosmomath.pyx
@@ -0,0 +1,38 @@
+import numpy as np
+cimport numpy as np
+
+np.import_array()
+np.import_ufunc()
+
+cdef extern from "sys/types.h":
+   ctypedef np.int64_t int64_t
+
+cdef extern from "special_math.hpp" namespace "CosmoTool":
+   T log_modified_bessel_first_kind[T](T v, T z) nogil except +
+
+
+cdef np.PyUFuncGenericFunction loop_func[1]
+cdef char input_output_types[3]
+cdef void *elementwise_funcs[1]
+
+loop_func[0] = np.PyUFunc_dd_d
+
+input_output_types[0] = np.NPY_DOUBLE
+input_output_types[1] = np.NPY_DOUBLE
+input_output_types[2] = np.NPY_DOUBLE
+
+elementwise_funcs[0] = <void*>log_modified_bessel_first_kind[double]
+
+log_modified_I = np.PyUFunc_FromFuncAndData(
+    loop_func,
+    elementwise_funcs,
+    input_output_types,
+    1, # number of supported input types
+    2, # number of input args
+    1, # number of output args
+    0, # `identity` element, never mind this
+    "log_modified_bessel_first_kind", # function name
+    "log_modified_bessel_first_kind(v: Float, z: Float) -> Float", # docstring
+    0 # unused
+    )
+
diff --git a/setup.py b/setup.py
index 6ed753e..6437ecf 100644
--- a/setup.py
+++ b/setup.py
@@ -218,7 +218,7 @@ class BuildCMakeExt(build_ext):
 CosmoTool_extension = CMakeExtension(name="cosmotool")
 
 setup(name='cosmotool',
-      version='1.0.0a8',
+      version='1.1.0',
       packages=["cosmotool"],
       package_dir={'cosmotool': 'python/cosmotool'},
       install_requires=['numpy','cffi','numexpr','pyfftw','h5py'],