forked from davecom/ClassicComputerScienceProblemsInPython
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathutil.py
More file actions
32 lines (26 loc) · 1 KB
/
util.py
File metadata and controls
32 lines (26 loc) · 1 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
# util.py
# From Classic Computer Science Problems in Python Chapter 7
# Copyright 2018 David Kopec
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from typing import List
from math import exp
# dot product of two vectors
def dot_product(xs: List[float], ys: List[float]) -> float:
return sum(x * y for x, y in zip(xs, ys))
# the classic sigmoid activation function
def sigmoid(x: float) -> float:
return 1.0 / (1.0 + exp(x))
def derivative_sigmoid(x: float) -> float:
sig = sigmoid(x)
return sig * (1 - sig)