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#1 2014-09-23 17:50:00
- HopeYouKnowWhoIam
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Please tell me
Please tell me if Coefficient[Product[(x+i),{i,100}],x,99] is 5050 because no CAS is working here?! help!!!!
#2 2014-09-23 18:40:30
- Bob
- Administrator
- Registered: 2010-06-20
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Re: Please tell me
hi HopeYouKnowWhoIam
Welcome to the forum. I, for one, don't know who you are. 
I also don't follow your syntax. What are you multiplying (x + i) by ?
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob 
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#3 2014-09-23 18:49:45
- anonimnystefy
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- From: Harlan's World
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Re: Please tell me
Hi Bob
It's M syntax. I'll try to run it, he basically wants the x^99 term of
Last edited by anonimnystefy (2014-09-23 18:55:04)
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#4 2014-09-23 18:54:15
- Bob
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Re: Please tell me
hi Stefy,
Thanks, I did wonder if that was the sort of thing meant.
Now is that i the 'summation' variable Ie the same as n in your version ?
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
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#5 2014-09-23 18:56:13
- Bob
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Re: Please tell me
What I mean is
is this (x+1)(x+2).....(x+100) or is it (x+i)^100 where i is a constant ?
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
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#6 2014-09-23 18:56:48
- anonimnystefy
- Real Member
- From: Harlan's World
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- Posts: 16,049
Re: Please tell me
Yes, it is, I have edited it accordingly.
If I am not mistaken, the x^99 term should be
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#7 2014-09-23 19:00:34
- Bob
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Re: Please tell me
The x^99 term will be found by picking 99 brackets with x and one bracket with a number and then adding them up. So the coefficient is
Who needs a CAS ?
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
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#8 2014-09-23 19:06:45
- anonimnystefy
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- From: Harlan's World
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Re: Please tell me
Ah, yes, that is correct. I was thinking of the x term.
Have you seen the thread that emerged?
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#9 2014-09-23 19:27:41
- Bob
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Re: Please tell me
Have you seen the thread that emerged?
?? Which thread ?
btw re-check your Latex in post 6.
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
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#10 2014-09-23 19:33:55
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
Re: Please tell me
What's wrong with my LaTeX?
What's my line?
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#11 2014-09-23 19:44:51
Re: Please tell me
Thank you, guys. It indeed is 5050. I did with combinatorics, I do not get the normal procedure anyway
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#12 2014-09-23 20:02:25
- anonimnystefy
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- From: Harlan's World
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Re: Please tell me
Is this a Brilliant problem?
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#13 2014-09-23 20:13:58
- Bob
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- Registered: 2010-06-20
- Posts: 10,127
Re: Please tell me
What's wrong with my LaTeX?
This is what I'm seeing:
So what is 1/i when i = 0 ?
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
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#14 2014-09-23 20:16:03
Re: Please tell me
It is not a Brilliant problem. But it will become one soon.
The next knows how
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#15 2014-09-23 20:19:32
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
Re: Please tell me
That's no a Latex problem, it's me not checking. It should go from i=1 and is the answer for the incorrect problem.
Yes, I know.
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.
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#16 2014-09-23 21:14:37
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Please tell me
Hi HopeYouKnowWhoIam;
I know who you are. Someone who ain't been reading my computer math thread.
Coefficient[Product[(x + i), {i, 100}] // Expand, x^99]is 5050 because no CAS is working here
There ain't nuthin a CAS can not do.
It is not a Brilliant problem. But it will become one soon.
Hoooha, I can not wait.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#17 2014-09-23 21:42:25
Re: Please tell me
The command he posted works too:
Coefficient[Product[(x+i),{i,100}],x,99]'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#18 2014-09-23 21:47:09
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Please tell me
It does not work.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#19 2014-09-23 21:52:21
Re: Please tell me
In[1]:= Timing[Coefficient[Product[(x + i), {i, 100}], x, 99]]
Out[1]= {21.056764, 5050} The OP is following your Computer Math thread. He could not get the CAS to work because he did not have it on the machine which he was using then.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#20 2014-09-23 21:54:32
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Please tell me
I repeat, that does not work. Efficiency counts.
AbsoluteTiming[Coefficient[Product[(x + i), {i, 100}], x, 99]]
AbsoluteTiming[Coefficient[Product[(x + i), {i, 100}] // Expand, x^99]]
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#21 2014-09-23 22:00:30
Re: Please tell me
Mathematicians like simplicity. I like speed. Your solution is neither simple nor fast.
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#22 2014-09-23 22:03:30
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Please tell me
It is over 40 times faster than the OP's solution on my machine! Please run the code.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#23 2014-09-23 22:09:09
Re: Please tell me
In[2]:= AbsoluteTiming[Coefficient[Product[(x + i), {i, 100}], x, 99]]
Out[2]= {20.849901, 5050}
In[3]:= AbsoluteTiming[
Coefficient[Product[(x + i), {i, 100}] // Expand, x^99]]
Out[3]= {0.008456, 5050}
In[5]:= %2/%3
Out[5]= {2466., 1} Do you know why he could not get the CAS working?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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#24 2014-09-23 22:12:08
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Please tell me
You seem to be agreeing with me... My solution is much faster and we can do better.
Do you know why he could not get the CAS working?
Who, what, when please.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#25 2014-09-23 22:32:26
Re: Please tell me
Who
I am talking about the OP.
when
Today 11:20 Indian Standard Time
what
What what?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
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