# minte9 LearnRemember

pag. 109-111

### Pythagorean Theorem

The goal of incremental development is to avoid long debugging. By Pythagorean Theorem, the distance between two points is: $d = \sqrt{(x2-x1)^2 + (y2-y1)^2}$

### Step 1


""" Step 1 / Incremental Development
Define the function, with wrong answer but syntactically correct
"""

def distance(x1, y1, x2, y2):
return 0.0

assert distance(1, 2, 4, 6) == 0.0
assert distance(1, 2, 1, 2) == 0.0
print("Asserts passed!")


### Step 2


""" Step 2 / Incremental Development
Find the differences x2-x1, y2-y1
"""

def distance(x1, y1, x2, y2):
dx = x2 - x1
dy = y2 - y1

return 0.0

assert distance(1, 2, 4, 6) == 0.0
assert distance(1, 2, 1, 2) == 0.0
print("Asserts passed!")


### Step 3


""" Step 3 / Incremental Development
Compute the sum of squares
"""

def distance(x1, y1, x2, y2):
dx = x2 - x1
dy = y2 - y1

sum = dx**2 + dy**2

return 0.0

assert distance(1, 2, 4, 6) == 0.0
assert distance(1, 2, 1, 2) == 0.0
print("Asserts passed!")


### Step 4


""" Step 4 / Incremental Development
Finally, use math.sqrt() to compute the result
"""

import math

def distance(x1, y1, x2, y2):
dx = x2 - x1
dy = y2 - y1

sum = dx**2 + dy**2

return math.sqrt(sum)

d = distance(1, 2, 4, 6)

assert distance(1, 2, 4, 6) == 5.0
assert distance(2, 2, 2, 6) == 4.0
print("Asserts passed!")


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