Re: [R] How to solve following equation?
Thanks for this reply, However I am interested to know why I need to modify
my function to a=1?
Regards,
Gabor Grothendieck wrote:
Assume a = 1. If not set b = b/a, etc.
Now use (1) uniroot
f - function(x) b + c/(1+x) + d/(1+x)^2 - 1 - x
uniroot(f, 0:1)
$root
[1] 0.8392679
$f.root
[1] 3.049818e-05
$iter
[1] 3
$estim.prec
[1] 6.103516e-05
or multiply through by 1+x
and subtract 1 from both sides giving
x = b + c/(1+x) + d/(1+x)^2 - 1
and iterate that.
a - b - c - d - 1
x - 0
for(i in 1:25) {
+ x - b + c/(1+x) + d/(1+x)^2 - 1
+ print(x)
+ }
[1] 2
[1] 0.444
[1] 1.171598
[1] 0.6725419
[1] 0.9553676
[1] 0.7729558
[1] 0.8821595
[1] 0.8135892
[1] 0.8554268
[1] 0.829437
[1] 0.8454056
[1] 0.835527
[1] 0.8416126
[1] 0.837854
[1] 0.8401717
[1] 0.838741
[1] 0.8396236
[1] 0.839079
[1] 0.839415
[1] 0.8392076
[1] 0.8393356
[1] 0.8392566
[1] 0.8393053
[1] 0.8392753
[1] 0.8392938
On Mon, Dec 1, 2008 at 9:47 PM, RON70 [EMAIL PROTECTED] wrote:
I need to solve a equation like this :
a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3
where a,b,c,d are known constant. Is there any R-way to do that?
Thanks in advance
--
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Re: [R] How to solve following equation?
You don't. This was just to make the presentation simpler.
On Wed, Dec 3, 2008 at 12:32 PM, RON70 [EMAIL PROTECTED] wrote:
Thanks for this reply, However I am interested to know why I need to modify
my function to a=1?
Regards,
Gabor Grothendieck wrote:
Assume a = 1. If not set b = b/a, etc.
Now use (1) uniroot
f - function(x) b + c/(1+x) + d/(1+x)^2 - 1 - x
uniroot(f, 0:1)
$root
[1] 0.8392679
$f.root
[1] 3.049818e-05
$iter
[1] 3
$estim.prec
[1] 6.103516e-05
or multiply through by 1+x
and subtract 1 from both sides giving
x = b + c/(1+x) + d/(1+x)^2 - 1
and iterate that.
a - b - c - d - 1
x - 0
for(i in 1:25) {
+ x - b + c/(1+x) + d/(1+x)^2 - 1
+ print(x)
+ }
[1] 2
[1] 0.444
[1] 1.171598
[1] 0.6725419
[1] 0.9553676
[1] 0.7729558
[1] 0.8821595
[1] 0.8135892
[1] 0.8554268
[1] 0.829437
[1] 0.8454056
[1] 0.835527
[1] 0.8416126
[1] 0.837854
[1] 0.8401717
[1] 0.838741
[1] 0.8396236
[1] 0.839079
[1] 0.839415
[1] 0.8392076
[1] 0.8393356
[1] 0.8392566
[1] 0.8393053
[1] 0.8392753
[1] 0.8392938
On Mon, Dec 1, 2008 at 9:47 PM, RON70 [EMAIL PROTECTED] wrote:
I need to solve a equation like this :
a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3
where a,b,c,d are known constant. Is there any R-way to do that?
Thanks in advance
--
View this message in context:
http://www.nabble.com/How-to-solve-following-equation--tp20785063p20785063.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
View this message in context:
http://www.nabble.com/How-to-solve-following-equation--tp20785063p20817656.html
Sent from the R help mailing list archive at Nabble.com.
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] How to solve following equation?
I need to solve a equation like this :
a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3
where a,b,c,d are known constant. Is there any R-way to do that?
Multiplying this expression with (1+x)^3 leads to a polynomial equation.
I would certainly recommend the 'PolynomF' package here:
# install.packages(PolynomF)
library(PolynomF)
options(digits=16)
x - polynom()
a - b - c - d - 1
p - a*(1+x)^3 - b*(1+x)^2 - c*(1+x) - d
p
# -2 + 2*x^2 + x^3
solve(p)
# [1] -1.419643377607080-0.6062907292072i
# -1.419643377607080+0.6062907292072i
# [3] 0.839286755214161+0.0i
The solution x0 = 0.839286755214161 is correct up to the last digit, as can be
verified by using a computer algebra system. This also shows that Ryacas is
quite exact in this task.
Hans Werner
Gabor Grothendieck ggrothendieck at gmail.com writes:
Assume a = 1. If not set b = b/a, etc.
Now use (1) uniroot
f - function(x) b + c/(1+x) + d/(1+x)^2 - 1 - x
uniroot(f, 0:1)
$root
[1] 0.8392679
$f.root
[1] 3.049818e-05
$iter
[1] 3
$estim.prec
[1] 6.103516e-05
or multiply through by 1+x
and subtract 1 from both sides giving
x = b + c/(1+x) + d/(1+x)^2 - 1
and iterate that.
a - b - c - d - 1
x - 0
for(i in 1:25) {
+ x - b + c/(1+x) + d/(1+x)^2 - 1
+ print(x)
+ }
[1] 2
[1] 0.444
[1] 1.171598
[1] 0.6725419
[1] 0.9553676
[1] 0.7729558
[1] 0.8821595
[1] 0.8135892
[1] 0.8554268
[1] 0.829437
[1] 0.8454056
[1] 0.835527
[1] 0.8416126
[1] 0.837854
[1] 0.8401717
[1] 0.838741
[1] 0.8396236
[1] 0.839079
[1] 0.839415
[1] 0.8392076
[1] 0.8393356
[1] 0.8392566
[1] 0.8393053
[1] 0.8392753
[1] 0.8392938
On Mon, Dec 1, 2008 at 9:47 PM, RON70 ron_michael70 at yahoo.com wrote:
I need to solve a equation like this :
a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3
where a,b,c,d are known constant. Is there any R-way to do that?
Thanks in advance
--
View this message in context:
http://www.nabble.com/How-to-solve-following-equation--tp20785063p20785063.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help at r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
__
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and provide commented, minimal, self-contained, reproducible code.
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
[R] How to solve following equation?
I need to solve a equation like this : a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3 where a,b,c,d are known constant. Is there any R-way to do that? Thanks in advance -- View this message in context: http://www.nabble.com/How-to-solve-following-equation--tp20785063p20785063.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] How to solve following equation?
Assume a = 1. If not set b = b/a, etc.
Now use (1) uniroot
f - function(x) b + c/(1+x) + d/(1+x)^2 - 1 - x
uniroot(f, 0:1)
$root
[1] 0.8392679
$f.root
[1] 3.049818e-05
$iter
[1] 3
$estim.prec
[1] 6.103516e-05
or multiply through by 1+x
and subtract 1 from both sides giving
x = b + c/(1+x) + d/(1+x)^2 - 1
and iterate that.
a - b - c - d - 1
x - 0
for(i in 1:25) {
+ x - b + c/(1+x) + d/(1+x)^2 - 1
+ print(x)
+ }
[1] 2
[1] 0.444
[1] 1.171598
[1] 0.6725419
[1] 0.9553676
[1] 0.7729558
[1] 0.8821595
[1] 0.8135892
[1] 0.8554268
[1] 0.829437
[1] 0.8454056
[1] 0.835527
[1] 0.8416126
[1] 0.837854
[1] 0.8401717
[1] 0.838741
[1] 0.8396236
[1] 0.839079
[1] 0.839415
[1] 0.8392076
[1] 0.8393356
[1] 0.8392566
[1] 0.8393053
[1] 0.8392753
[1] 0.8392938
On Mon, Dec 1, 2008 at 9:47 PM, RON70 [EMAIL PROTECTED] wrote:
I need to solve a equation like this :
a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3
where a,b,c,d are known constant. Is there any R-way to do that?
Thanks in advance
--
View this message in context:
http://www.nabble.com/How-to-solve-following-equation--tp20785063p20785063.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
__
R-help@r-project.org mailing list
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and provide commented, minimal, self-contained, reproducible code.
Re: [R] How to solve following equation?
Dear RON70, Another approach would be Ryacas [1]. Take a look at Section 5.3.2: yacas(Newton((1+x)^3-(1+x)^2-(1+x)-1,x,0.1,0.1)) expression(0.839286755214161) Note that this result is _similar_ to Gabor Grothendieck's solution using optim(). HTH, Jorge [1] http://cran.r-project.org/web/packages/Ryacas/index.html On Mon, Dec 1, 2008 at 9:47 PM, RON70 [EMAIL PROTECTED] wrote: I need to solve a equation like this : a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3 where a,b,c,d are known constant. Is there any R-way to do that? Thanks in advance -- View this message in context: http://www.nabble.com/How-to-solve-following-equation--tp20785063p20785063.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
