ShmoopTube

00:00

Thank you We sneak and here's your smoke Use your

00:05

with your floating point joke of the day Why was

00:08

six afraid of seven Because seven eight over we'll go

00:13

to nine all right okay how can you change the

00:17

code to avoid issues if there are any this coat

00:20

right here and here the potential answers Paul's waver All

00:26

right let's go So we're being asked how we change

00:28

this code to avoid potential issues If there are any

00:31

the code intends to run this four loop one hundred

00:34

times and perform a simple mathematical operation on numb each

00:38

time Well no um which starts at zero point one

00:41

is the divisor of one which gives us ten Then

00:44

we subtract nine point nine from that in typical human

00:47

style mathematics this would mean the result is your appoint

00:50

one Then it loops again This time around Nome is

00:53

point one again and again and again until Luke runs

00:56

100 times numb Seems like it should always wind up

00:59

back at zero point one but that's not how it

01:02

works in practice There are issues with his code to

01:06

put it mildly that double we declare it The outset

01:08

is a floating point variable ding dinging five dollar words

01:12

which means it'll be extremely close but never quite exactly

01:15

the number we expect In fact in the video for

01:18

the previous question we explored what's happening more closely and

01:21

here's how numb changes with each iteration ugly So the

01:26

floating point uncertainty gets greater and greater Over time until

01:29

the whole thing more less breaks down unless the programmers

01:32

idea was to get negative ten in the most around

01:35

about confusing way possible Well this code does not work

01:38

so let's look at possible solutions okay used rule ian

01:41

values instead of double Well not quite Julian values are

01:44

either true or false and not designed for numbers be

01:48

used imagers instead of double Well now that's pretty reasonable

01:51

solution Actually of course we've learned in injuries aren't capable

01:54

of decimal places that we'd have to use nothing but

01:57

whole numbers But if we just did a couple of

01:59

tweets to the code here in there and move decimal

02:02

places over one space to create whole numbers well hey

02:05

there we go and this would actually work to we'd

02:08

still get our double that equals zero point one in

02:10

the form of numb to that worked Clever well let's

02:13

go with b but check the others just in case

02:15

option c andy or interesting in that they could be

02:17

used to avoid the problem but not fix it It's

02:20

like saying the bathroom is broken so just go outside

02:23

Okay We've done that before which is to say it

02:27

might work in an emergency at two thirty in the

02:29

morning when the neighbours won't see But it's not a

02:32

real solution Trust us Bad things can happen Long story

02:36

All right option eat There aren't any issues with coat

02:40

Well that's very funny option He really hilarious So let's

02:43

make a mental note not to invite option eating any 00:02:45.185 --> [endTime] more of these things by you

Full Transcript