similar to: evaluation of equations from Ryacas

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: >

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:

Hi R People: Is there a package for automatic differentiation, please? thanks in advance, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodgess at gmail.com

Dear R people: Is there a way to perform simple polynomial multiplication; that is, something like (x - 3) * (x + 3) = x^2 - 9, please? I looked in poly and polyroot and expression. There used to be a package that had this, maybe? thanks, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodgess at

Dear R People: Hope you're having a nice day. Here is a character vector: > yz [1] "pexp(3.2,rate=1)" > str(yz) chr "pexp(3.2,rate=1)" > And I would like to evaluate that vector. I tried: > eval(as.expression(yz)) [1] "pexp(3.2,rate=1)" > But that doesn't work. Any suggestions would be most welcome. I have a feeling that it's quite

Dear R People: Here is a toy example: > x <- c("2E","5W","12H") > substr(x,2,2) [1] "E" "W" "2" > Sometimes x has 3 elements, sometimes 2. I want to extract the last element, and then extract the other 1 or 2 elements. How can I do this, please? TIA, Sincerely, Erin -- Erin Hodgess Associate Professor Department of

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

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

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

Dear R People: I have a data frame, xm1, which has 12 rows and 4 columns. If I put is xm1[,-4], I get all rows, and columns 1 - 3, which is as it should be. Now, is there a way to use the names of the columns to omit them, please? Thanks so much in advance! Sincerely, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown

Hi again. I'm putting together a little project with R, python, and a website. So I have an HTML file, a py file, an R file. Here is the HTML file: <form action="/cgi-bin/radio4.py" method="post" target="_blank"> <input type="radio" name="subject" value="Integrate" /> Integrate <input type="radio"

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]

Everything is ok on Firefox, IE, and iPad. Thanks, Erin On Tue, Jan 8, 2013 at 7:58 PM, Erin Hodgess <erinm.hodgess at gmail.com> wrote: > Dear R People: > > Has anyone used R2HTML in web files that were on the Blackboard LMS, please? > > I'm starting to do these but wanted to know if there were any > potential pitfalls. > > Thanks, > Erin > > > --

Dear R People: Here is a goofy question: I want to extract the zip code from an address and here is my work so far: > add1 results.formatted_address "200 W Rosamond St, Houston, TX 77076, USA" > add1[1][32:36] <NA> <NA> <NA> <NA> <NA> NA NA NA NA NA > str(add1) Named chr "200 W Rosamond St, Houston, TX 77076,

Hello I would like to build R from source and use the PGI compiler, rather than the GCC compiler. I saw the instructions for the Intel compiler in the R Installation Manual, but I didn't see the PGI. I tried a few times without instructions, but without success. Any suggestions would be most welcome. Also, I hope this is the right group for the question. Sincerely, Erin -- Erin

Dear R People: Here is something that I am sure is very simple. I'm just trying to re-create the C convolution example in the Extensions manual. Here is the subroutine: void convolve(double *a, int *na, double *b, int *nb, double *ab) { R_len_t i, j, nab = *na + *nb - 1; for(i = 0; i < nab; i++) ab[i] = 0.0; for(i = 0; i < *na; i++) for(j = 0; j < *nb; j++) ab[i + j] += a[i] *

Dear R People: I have generated the following table: > table(zza$DEATH,zza$GENDER) F M 2009-04-21 0 1 2009-04-22 4 2 2009-04-24 6 0 2009-04-25 1 3 2009-04-26 2 0 2009-04-28 3 0 2009-04-29 2 2 However, instead of total counts in the F and M columns, I would like percents. How would I do this, please? thanks, Erin -- Erin

I believe that repo just follows the directions on my blog. Without seeing Dr. Hodges?s code, my initial concern is the many references to Cygwin. My method specifically does not use Cygwin but MSYS2 and Mingw64/Rtools35. That will likely change to solely Rtools40 once R3.6 is released due to the Msys system being built in to it. There may be some library conflicts between Cygwin and

Dear R People: When I want to produce a small sample confidence interval using t.test, I get the following: > t.test(buzz$var1, conf.level=.98)$conf.int [1] 2.239337 4.260663 attr(,"conf.level") [1] 0.98 How do I keep the attr statement from printing, please? I'm sure it's something really simple. Thanks, Sincerely, Erin -- Erin Hodgess Associate Professor Department

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