# 1.2 Machine learning lecture 3  (Page 2/14)

You can actually take this even further, right? Which is – let’s see. I have seven training examples here, so you can actually maybe fit up to six for the polynomial. You can actually fill a model theta zero plus theta one, X1 plus theta two, X squared plus up to theta six. X to the power of six and theta six are the polynomial to these seven data points. And if you do that you find that you come up with a model that fits your data exactly. This is where, I guess, in this example I drew, we have seven data points, so if you fit a six model polynomial you can, sort of, fit a line that passes through these seven points perfectly. And you probably find that the curve you get will look something like that. And on the one hand, this is a great model in a sense that it fits your training data perfectly. On the other hand, this is probably not a very good model in the sense that none of us seriously think that this is a very good predictor of housing prices as a function of the size of the house, right?

So we’ll actually come back to this later. It turns out of the models we have here; I feel like maybe the quadratic model fits the data best. Whereas the linear model looks like there’s actually a bit of a quadratic component in this data that the linear function is not capturing. So we’ll actually come back to this a little bit later and talk about the problems associated with fitting models that are either too simple, use two small a set of features, or on the models that are too complex and maybe use too large a set of features. Just to give these a name, we call this the problem of underfitting and, very informally, this refers to a setting where there are obvious patterns that – where there are patterns in the data that the algorithm is just failing to fit. And this problem here we refer to as overfitting and, again, very informally, this is when the algorithm is fitting the idiosyncrasies of this specific data set, right? It just so happens that of the seven houses we sampled in Portland, or wherever you collect data from, that house happens to be a bit more expensive, that house happened on the less expensive, and by fitting six for the polynomial we’re, sort of, fitting the idiosyncratic properties of this data set, rather than the true underlying trends of how housing prices vary as the function of the size of house. Okay?

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
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