如何使用带有海龟图形的Python制作线性图形计算器？

Question

Why doesn't this code work when I try to graph? The y-intercept doesn't seem to work.

from turtle import *

m = float(input("What is the slope? "))

b = float(input("What is the y-intercept? "))

x= window_width()

y= window_height()

y= int(m*x + b)

pd()

goto(x , y)

pd()

goto(-x,-y)

pu()

goto(x/2,0)

pd()

goto(-x/2,0)


pu()

goto(0,2*y)

pd()

goto(0,-2*y)

update()

When I test values with y-intercepts, they go throgh the origin, which means it's not working. I'm trying to get the y-intercept working.

Answer 1

Why doesn't this code work when I try to graph?

I see two issues: 1) you seem to be doing things in the wrong order; 2) you incorrectly assume that if y is f(x) then f(-x) is -y which isn't true:

from turtle import *

m = float(input("What is the slope? "))

b = float(input("What is the y-intercept? "))

x, y = window_width(), window_height()

# Draw Axes
penup()
goto(x / 2, 0)
pendown()
goto(-x / 2, 0)
penup()
goto(0, y / 2)
pendown()
goto(0, -y / 2)

# Plot function

y = int(m * x + b)

penup()
goto(x, y)

x = -x
y = int(m * x + b)

pendown()
goto(x, y)

done()

USAGE

> python3 test.py
What is the slope? 0.5
What is the y-intercept? 100
>

OUTPUT