Hi all, I need to solve this following equation which the unknown value (here is "a") is on the exponent place, could anybody please help me to figure it out? I tried to use lm.sol() or solve() function but it doesn't work...... Thanks for help, Peiling (x, y) = (2.21, 1.01) y = 1 + x - ( 1 + (x)^a)^(1/a)
solve the equation in R
4 messages · Pei-Ling Lin, R. Michael Weylandt, Petr Savicky +1 more
You could probably find a way to do this using nls(), optim() or uniroot() but this seems to be very much a homework problem so I won't say more. solve() solves matrix linear equations... not what you want here. Read the docs. Michael
On Thu, May 17, 2012 at 2:53 PM, Pei-Ling Lin <barthealin at gmail.com> wrote:
Hi all, I need to solve this following equation which the unknown value (here is "a") is on the exponent place, could anybody please help me to figure it out? I tried to use lm.sol() or solve() function but it doesn't work...... Thanks for help, Peiling ?(x, ? y) = (2.21, 1.01) ?y = 1 + x - ( 1 + (x)^a)^(1/a)
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On Thu, May 17, 2012 at 01:53:39PM -0500, Pei-Ling Lin wrote:
Hi all, I need to solve this following equation which the unknown value (here is "a") is on the exponent place, could anybody please help me to figure it out? I tried to use lm.sol() or solve() function but it doesn't work...... Thanks for help, Peiling (x, y) = (2.21, 1.01) y = 1 + x - ( 1 + (x)^a)^(1/a)
Hi.
First, plot the function
f <- function(a) { 1 + x - ( 1 + (x)^a)^(1/a) - y }
x <- 2.21
y <- 1.01
a <- seq(0.1, 20, length=1000)
plot(a, f(a), ylim=c(-0.2, 0.2), type="l")
abline(h=0)
This suggests, that there is no root. This may also be obtained
analytically.
Hope this helps.
Petr Savicky.
On 17-May-2012 21:50:17 Petr Savicky wrote:
On Thu, May 17, 2012 at 01:53:39PM -0500, Pei-Ling Lin wrote:
Hi all, I need to solve this following equation which the unknown value (here is "a") is on the exponent place, could anybody please help me to figure it out? I tried to use lm.sol() or solve() function but it doesn't work...... Thanks for help, Peiling (x, y) = (2.21, 1.01) y = 1 + x - ( 1 + (x)^a)^(1/a)
Hi.
First, plot the function
f <- function(a) { 1 + x - ( 1 + (x)^a)^(1/a) - y }
x <- 2.21
y <- 1.01
a <- seq(0.1, 20, length=1000)
plot(a, f(a), ylim=c(-0.2, 0.2), type="l")
abline(h=0)
This suggests, that there is no root. This may also be obtained
analytically.
Hope this helps.
Petr Savicky.
Well, certainly no solution for Y > 1. But if y < 1 then there is a solution. Was the problem stated correctly? Ted. ------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding at wlandres.net> Date: 17-May-2012 Time: 23:27:09 This message was sent by XFMail