similar to: Solving Equations

Displaying 20 results from an estimated 1000 matches similar to: "Solving Equations"

2003 Feb 28
2
optim
Dear all, I have a function MYFUN which depends on 3 positive parameters TETA[1], TETA[2], and TETA[3]; x belongs to [0,1]. I integrate the function over [0,0.1], [0.1,0.2] and [0.2,0.3] and want to choose the three parameters so that these three integrals are as close to, resp., 2300, 4600 and 5800 as possible. As I have three equations with three unknowns, I expect the exact fit, i.e., the SS
2006 Jul 04
1
Problems when computing the 1rst derivative of mixtures of densities
Hi everybody, I am currently working on mixtures of two densities ( f(xi,teta)= (1-teta)*f1(xi) + teta*f2(xi) ), particularly on the behavior of the variance for teta=0 (so sample only comes from the first distribution). To determine the maximum likelihood estimator I use the Newton-Rapdon Iteration. But when computing the first derivative I get a none linear function (with several asymptotes)
2012 Aug 16
1
Symbolic computation in R-solving system of equations
Hi, To my knowledge, Ryacas can do symbolic computation in R, like Mathematica or Maple. I wonder if it (or any other R package) can solve symbolically a system of equations? I have a system of four equations in four variables (non-linear, but not very hard to solve) and wonder if Ryacas or any other package can do it. I do not find the solution in Ryacas. Can it find a symbolic solution
2006 Oct 16
2
New package Ryacas
Ryacas is an R interface to the free yacas computer algebra system. Ryacas allows one to send R expressions, unprocessed yacas strings and certain other R objects to a separate yacas process from R and get back the result. It also has facilities for manipulating yacas strings and R expressions destined for yacas processing. It can be used for exact arithmetic, symbolic math, ASCII pretty
2006 Oct 16
2
New package Ryacas
Ryacas is an R interface to the free yacas computer algebra system. Ryacas allows one to send R expressions, unprocessed yacas strings and certain other R objects to a separate yacas process from R and get back the result. It also has facilities for manipulating yacas strings and R expressions destined for yacas processing. It can be used for exact arithmetic, symbolic math, ASCII pretty
2006 Oct 16
2
New package Ryacas
Ryacas is an R interface to the free yacas computer algebra system. Ryacas allows one to send R expressions, unprocessed yacas strings and certain other R objects to a separate yacas process from R and get back the result. It also has facilities for manipulating yacas strings and R expressions destined for yacas processing. It can be used for exact arithmetic, symbolic math, ASCII pretty
2006 Nov 23
4
Ryacas and fractions with simultaenously very large numerators and denominators
Dear All I am doing the following: > x <- yacas("3/2") > for (i in 2:400) + x <- yacas(paste(x,"*",x)) > x expression(Inf^1.260864167e+117/Inf^6.304320836e+116) > Eval(x) [1] NaN No luck this way. However, I am successful with > y <- yacas("(3/2)^400") > y expression(7.05507910865533e+190/2.58224987808691e+120) > Eval(y) [1]
2013 Jun 19
2
evaluation of equations from Ryacas
Hello again. Now I have the following: > xx [1] "Solve(1 - R/100==(2*y)/10000,R)" > yacas(xx) expression(list(R == 100 * (1 - 2 * y/10000))) > I would like to put in a value for y and obtain R. I've tried more stuff with eval and Eval, but no luck yet. Any suggestions would be much appreciated. Thanks, Erin -- Erin Hodgess Associate Professor Department of Computer
2013 Jun 19
2
Ryacas loads but yacas has an error
Hello yet again, R People: I was working with Ryacas and yacas last night and all was well. Now this morning, I keep getting the following: > a <- Sym("a") > a Error in summary.connection(x) : invalid connection > When I go to yacas from the command line, it works fine. Any suggestions, please? I'm thinking that a port might be open, but here I have: >
2012 Dec 05
1
loading & using Ryacas
I'm having trouble loading Ryacas. I've downloaded and extracted Ryacas 0.2-9 (also tried Ryacas ) and yacas 1.0.63, have the latest version of R and have tried the following (this works for installing other packages): install.packages("Ryacas") library(Ryacas) install.packages("yacas") library(yacas) and get this: Warning message: package ‘yacas’ is not available
2012 Sep 04
3
Ryacas
I am having issues with Ryacas errors. I searched and found this error was reported in 2006, but nothing since. > library(Ryacas) Loading required package: XML > yacas(expression(Factor(x^2-1))) [1] "Starting Yacas!" CommandLine(1) : Expecting ) closing bracket for sub-expression, but got ^ instead > yacas("D(x)Sin(x)") CommandLine(1) : Expecting ) closing bracket
2013 Jun 19
1
solving equations symbolically
Dear R People: I have the following equation: $1 - \frac{R}{100} = \frac{2y}{10000}$ and I was wondering if there was a way in R to solve for R (no pun intended). I'm experimenting with Ryacas, but nothing yet. Version R-3.0.1 on Windows 7. Thanks, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto:
2007 Sep 03
2
Derivative of a Function Expression
Hi I am currently (for pedagogical purposes) writing a simple numerical analysis library in R. I have come unstuck when writing a simple Newton-Raphson implementation, that looks like this: f <- function(x) { 2*cos(x)^2 + 3*sin(x) + 0.5 } root <- newton(f, tol=0.0001, N=20, a=1) My issue is calculating the symbolic derivative of f() inside the newton() function. I cant seem to get R to
2017 Sep 19
1
symbolic computing example with Ryacas
Thanks for the response. Yes, I did study the vignette but did not understand it fully. Anyway, I have tried once again now. I am happy to say that I have got what I wanted. library(Ryacas) x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C") my_func <- function(x,U,x0,C) { return (U/(1+exp(-(x-x0)/C)))} FirstDeriv <-
2017 Sep 19
2
symbolic computing example with Ryacas
Hi all, I am trying to implement the following matlab code with Ryacas : syms U x x0 C d1=diff(U/(1+exp(-(x-x0)/C)),x); pretty(d1) d2=diff(U/(1+exp(-(x-x0)/C)),x,2); pretty(d2) solx2 = solve(d2 == 0, x, 'Real', true) pretty(solx2) slope2=subs(d1,solx2) I have tried the following : library(Ryacas) x <- Sym("x");U <- Sym("U");x0 <-
2008 Jan 24
1
Ryacas behaving weird
There is either something wrong with either me or is Yacas/Ryacas doing odd things. See below I ask to simpify an expression and the there's output! If this is a simplification.. well.. Do you think there is something set wrong somewhere. Thanks. > library(Ryacas) Loading required package: XML > a=Sym("a") > N=Sym("N") > b=Sym("b") >
2010 Aug 26
1
equalize function with zero and convert it
Dear all, I want to equalize a symbolic derivative (of a function with two variables) with zero and convert it to a variable, e.g. x. I'm computing the derivative by: (found it in the archive) library(Ryacas) f <- function(x,y) (100-x-y)*x-10*x yacas(f) # register f with yacas Df <- f body(Df) <- yacas(expression(deriv(f(x,y),x)))[[1]] Df R-Output: function (x, y) 100 - x - y -
2017 Sep 19
0
symbolic computing example with Ryacas
Have you studied the "Introduction to Ryacas" vignette that come with the package? Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Tue, Sep 19, 2017 at 2:37 AM, Vivek Sutradhara <viveksutra at gmail.com> wrote:
2008 Jan 31
1
Ryacas
I'm tinkering around in Ryacas trying to find an easy way to get the first and second partial derivatives of mu and sigma from a normal distribution (actually a bitterly ugly likelihood but this example works for now). I've done all of the work in Mathematica, but I then need to manually write R code whereas I think Ryacas will give me the expression such that I can export for Tex and
2009 May 05
1
yacas
Hi, as I find problems with yacas package... is there any R function equivalent to the yacas function "Factor" ? the factor function which i found in the R help is not the same. it doesn't factor an algebraic expression...... thanks hassan [[alternative HTML version deleted]]