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Find n from summation
Find the original function in a summationSummation of $i cdot j$ from $ 1$ to$ 3$Evaluating Summation of $5^-n$ from $n=4$ to infinityExtract a variable from the following summationCalculating summation on integer numbers from $-infty$ to $infty$Order of growth from summationHow to solve this summation derived from an algorithm?M/G/1 queue: difference between $p_o$ and $p(0)$?How to find closed form of summationProof of identity about generalized binomial sequences.
$begingroup$
I ran into this expression while reading through a chapter a book:
$$sum_i=0^nfrace^-15001500^ii! ge 0.95$$
And they solve for $n$ and got $n = 1564$ from the expression, but there's no detail on how to get $n$. Can someone explain how to get that number for $n$?
The book is Discrete Event System Simulation by Jerry Banks. This is in the 5th Edition, Chapter 6 Example 6.15, if anyone wants to look this up.
summation poisson-distribution
$endgroup$
add a comment |
$begingroup$
I ran into this expression while reading through a chapter a book:
$$sum_i=0^nfrace^-15001500^ii! ge 0.95$$
And they solve for $n$ and got $n = 1564$ from the expression, but there's no detail on how to get $n$. Can someone explain how to get that number for $n$?
The book is Discrete Event System Simulation by Jerry Banks. This is in the 5th Edition, Chapter 6 Example 6.15, if anyone wants to look this up.
summation poisson-distribution
$endgroup$
$begingroup$
Is it possible the author used Mathematica (or some other mathematical software) to determine $n$? I can offer one or two techniques to solve for some such $n$, but I'm not sure anything is quite as tight as $n=1564$.
$endgroup$
– Clayton
yesterday
$begingroup$
That might have been the case. I tried to crunch this in wolfram alpha and couldn't get the answer.
$endgroup$
– PTN
yesterday
3
$begingroup$
The Poisson probability distribution for a mean of 1500 will be approximately a normal distribution. The probability to be 1.64485 sigma above the mean is 5% for a normal distribution, therefore you would roughly estimate n to be $1500 + 1.64485 sqrt1500approx 1564$
$endgroup$
– Count Iblis
yesterday
$begingroup$
@CountIblis That makes sense!
$endgroup$
– PTN
yesterday
add a comment |
$begingroup$
I ran into this expression while reading through a chapter a book:
$$sum_i=0^nfrace^-15001500^ii! ge 0.95$$
And they solve for $n$ and got $n = 1564$ from the expression, but there's no detail on how to get $n$. Can someone explain how to get that number for $n$?
The book is Discrete Event System Simulation by Jerry Banks. This is in the 5th Edition, Chapter 6 Example 6.15, if anyone wants to look this up.
summation poisson-distribution
$endgroup$
I ran into this expression while reading through a chapter a book:
$$sum_i=0^nfrace^-15001500^ii! ge 0.95$$
And they solve for $n$ and got $n = 1564$ from the expression, but there's no detail on how to get $n$. Can someone explain how to get that number for $n$?
The book is Discrete Event System Simulation by Jerry Banks. This is in the 5th Edition, Chapter 6 Example 6.15, if anyone wants to look this up.
summation poisson-distribution
summation poisson-distribution
edited yesterday
PTN
asked yesterday
PTNPTN
1496
1496
$begingroup$
Is it possible the author used Mathematica (or some other mathematical software) to determine $n$? I can offer one or two techniques to solve for some such $n$, but I'm not sure anything is quite as tight as $n=1564$.
$endgroup$
– Clayton
yesterday
$begingroup$
That might have been the case. I tried to crunch this in wolfram alpha and couldn't get the answer.
$endgroup$
– PTN
yesterday
3
$begingroup$
The Poisson probability distribution for a mean of 1500 will be approximately a normal distribution. The probability to be 1.64485 sigma above the mean is 5% for a normal distribution, therefore you would roughly estimate n to be $1500 + 1.64485 sqrt1500approx 1564$
$endgroup$
– Count Iblis
yesterday
$begingroup$
@CountIblis That makes sense!
$endgroup$
– PTN
yesterday
add a comment |
$begingroup$
Is it possible the author used Mathematica (or some other mathematical software) to determine $n$? I can offer one or two techniques to solve for some such $n$, but I'm not sure anything is quite as tight as $n=1564$.
$endgroup$
– Clayton
yesterday
$begingroup$
That might have been the case. I tried to crunch this in wolfram alpha and couldn't get the answer.
$endgroup$
– PTN
yesterday
3
$begingroup$
The Poisson probability distribution for a mean of 1500 will be approximately a normal distribution. The probability to be 1.64485 sigma above the mean is 5% for a normal distribution, therefore you would roughly estimate n to be $1500 + 1.64485 sqrt1500approx 1564$
$endgroup$
– Count Iblis
yesterday
$begingroup$
@CountIblis That makes sense!
$endgroup$
– PTN
yesterday
$begingroup$
Is it possible the author used Mathematica (or some other mathematical software) to determine $n$? I can offer one or two techniques to solve for some such $n$, but I'm not sure anything is quite as tight as $n=1564$.
$endgroup$
– Clayton
yesterday
$begingroup$
Is it possible the author used Mathematica (or some other mathematical software) to determine $n$? I can offer one or two techniques to solve for some such $n$, but I'm not sure anything is quite as tight as $n=1564$.
$endgroup$
– Clayton
yesterday
$begingroup$
That might have been the case. I tried to crunch this in wolfram alpha and couldn't get the answer.
$endgroup$
– PTN
yesterday
$begingroup$
That might have been the case. I tried to crunch this in wolfram alpha and couldn't get the answer.
$endgroup$
– PTN
yesterday
3
3
$begingroup$
The Poisson probability distribution for a mean of 1500 will be approximately a normal distribution. The probability to be 1.64485 sigma above the mean is 5% for a normal distribution, therefore you would roughly estimate n to be $1500 + 1.64485 sqrt1500approx 1564$
$endgroup$
– Count Iblis
yesterday
$begingroup$
The Poisson probability distribution for a mean of 1500 will be approximately a normal distribution. The probability to be 1.64485 sigma above the mean is 5% for a normal distribution, therefore you would roughly estimate n to be $1500 + 1.64485 sqrt1500approx 1564$
$endgroup$
– Count Iblis
yesterday
$begingroup$
@CountIblis That makes sense!
$endgroup$
– PTN
yesterday
$begingroup$
@CountIblis That makes sense!
$endgroup$
– PTN
yesterday
add a comment |
2 Answers
2
active
oldest
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$begingroup$
The probability distribution is the Poisson distribution with $lambda=1500$. For large $lambda$ the distribution is approximately normal with mean $lambda$ and variance $lambda$, so standard deviation $sigma=sqrt lambda$. For a one-sided normal distribution you have $5%$ of the area above mean + $1.648 sigma$, which here is $1500+1.648 sqrt 1500 approx 1564$
$endgroup$
add a comment |
$begingroup$
From a purely algebraic point of view
$$sum_i=0^nfrace^-15001500^ii! =fracGamma (n+1,1500)Gamma (n+1)$$ So, you could consider that we look for the zero of function
$$f(x)=fracGamma (x+1,1500)Gamma (x+1)-0.95$$ which is not very well conditioned. Better will be to search for the zero of
$$g(x)=log left(fracGamma (x+1,1500)Gamma (x+1)right)-log(0.95)$$ Remembering that
$fracGamma (m,m)Gamma (m) < frac 12$, let us use Newton method with $x_0=1500$. Since $g(x_0) <0$ and $g''(x_0) <0$, by Darboux theorem, we shall not face any overshoot of the solution which is $x=1563.485020$.
Just for the fun of it, ask Wolfram Alpha to plot $g(x)$ for $1500 leq x leq 1600$.
$endgroup$
add a comment |
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2 Answers
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2 Answers
2
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$begingroup$
The probability distribution is the Poisson distribution with $lambda=1500$. For large $lambda$ the distribution is approximately normal with mean $lambda$ and variance $lambda$, so standard deviation $sigma=sqrt lambda$. For a one-sided normal distribution you have $5%$ of the area above mean + $1.648 sigma$, which here is $1500+1.648 sqrt 1500 approx 1564$
$endgroup$
add a comment |
$begingroup$
The probability distribution is the Poisson distribution with $lambda=1500$. For large $lambda$ the distribution is approximately normal with mean $lambda$ and variance $lambda$, so standard deviation $sigma=sqrt lambda$. For a one-sided normal distribution you have $5%$ of the area above mean + $1.648 sigma$, which here is $1500+1.648 sqrt 1500 approx 1564$
$endgroup$
add a comment |
$begingroup$
The probability distribution is the Poisson distribution with $lambda=1500$. For large $lambda$ the distribution is approximately normal with mean $lambda$ and variance $lambda$, so standard deviation $sigma=sqrt lambda$. For a one-sided normal distribution you have $5%$ of the area above mean + $1.648 sigma$, which here is $1500+1.648 sqrt 1500 approx 1564$
$endgroup$
The probability distribution is the Poisson distribution with $lambda=1500$. For large $lambda$ the distribution is approximately normal with mean $lambda$ and variance $lambda$, so standard deviation $sigma=sqrt lambda$. For a one-sided normal distribution you have $5%$ of the area above mean + $1.648 sigma$, which here is $1500+1.648 sqrt 1500 approx 1564$
answered yesterday
Ross MillikanRoss Millikan
300k24200375
300k24200375
add a comment |
add a comment |
$begingroup$
From a purely algebraic point of view
$$sum_i=0^nfrace^-15001500^ii! =fracGamma (n+1,1500)Gamma (n+1)$$ So, you could consider that we look for the zero of function
$$f(x)=fracGamma (x+1,1500)Gamma (x+1)-0.95$$ which is not very well conditioned. Better will be to search for the zero of
$$g(x)=log left(fracGamma (x+1,1500)Gamma (x+1)right)-log(0.95)$$ Remembering that
$fracGamma (m,m)Gamma (m) < frac 12$, let us use Newton method with $x_0=1500$. Since $g(x_0) <0$ and $g''(x_0) <0$, by Darboux theorem, we shall not face any overshoot of the solution which is $x=1563.485020$.
Just for the fun of it, ask Wolfram Alpha to plot $g(x)$ for $1500 leq x leq 1600$.
$endgroup$
add a comment |
$begingroup$
From a purely algebraic point of view
$$sum_i=0^nfrace^-15001500^ii! =fracGamma (n+1,1500)Gamma (n+1)$$ So, you could consider that we look for the zero of function
$$f(x)=fracGamma (x+1,1500)Gamma (x+1)-0.95$$ which is not very well conditioned. Better will be to search for the zero of
$$g(x)=log left(fracGamma (x+1,1500)Gamma (x+1)right)-log(0.95)$$ Remembering that
$fracGamma (m,m)Gamma (m) < frac 12$, let us use Newton method with $x_0=1500$. Since $g(x_0) <0$ and $g''(x_0) <0$, by Darboux theorem, we shall not face any overshoot of the solution which is $x=1563.485020$.
Just for the fun of it, ask Wolfram Alpha to plot $g(x)$ for $1500 leq x leq 1600$.
$endgroup$
add a comment |
$begingroup$
From a purely algebraic point of view
$$sum_i=0^nfrace^-15001500^ii! =fracGamma (n+1,1500)Gamma (n+1)$$ So, you could consider that we look for the zero of function
$$f(x)=fracGamma (x+1,1500)Gamma (x+1)-0.95$$ which is not very well conditioned. Better will be to search for the zero of
$$g(x)=log left(fracGamma (x+1,1500)Gamma (x+1)right)-log(0.95)$$ Remembering that
$fracGamma (m,m)Gamma (m) < frac 12$, let us use Newton method with $x_0=1500$. Since $g(x_0) <0$ and $g''(x_0) <0$, by Darboux theorem, we shall not face any overshoot of the solution which is $x=1563.485020$.
Just for the fun of it, ask Wolfram Alpha to plot $g(x)$ for $1500 leq x leq 1600$.
$endgroup$
From a purely algebraic point of view
$$sum_i=0^nfrace^-15001500^ii! =fracGamma (n+1,1500)Gamma (n+1)$$ So, you could consider that we look for the zero of function
$$f(x)=fracGamma (x+1,1500)Gamma (x+1)-0.95$$ which is not very well conditioned. Better will be to search for the zero of
$$g(x)=log left(fracGamma (x+1,1500)Gamma (x+1)right)-log(0.95)$$ Remembering that
$fracGamma (m,m)Gamma (m) < frac 12$, let us use Newton method with $x_0=1500$. Since $g(x_0) <0$ and $g''(x_0) <0$, by Darboux theorem, we shall not face any overshoot of the solution which is $x=1563.485020$.
Just for the fun of it, ask Wolfram Alpha to plot $g(x)$ for $1500 leq x leq 1600$.
answered 21 hours ago
Claude LeiboviciClaude Leibovici
125k1158135
125k1158135
add a comment |
add a comment |
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$begingroup$
Is it possible the author used Mathematica (or some other mathematical software) to determine $n$? I can offer one or two techniques to solve for some such $n$, but I'm not sure anything is quite as tight as $n=1564$.
$endgroup$
– Clayton
yesterday
$begingroup$
That might have been the case. I tried to crunch this in wolfram alpha and couldn't get the answer.
$endgroup$
– PTN
yesterday
3
$begingroup$
The Poisson probability distribution for a mean of 1500 will be approximately a normal distribution. The probability to be 1.64485 sigma above the mean is 5% for a normal distribution, therefore you would roughly estimate n to be $1500 + 1.64485 sqrt1500approx 1564$
$endgroup$
– Count Iblis
yesterday
$begingroup$
@CountIblis That makes sense!
$endgroup$
– PTN
yesterday