Hi Seyed. I've runned your script and I haven't any mistake:

##

> install.packages("rootSolve")

Installing package into ‘C:/Users/GIC 76/Documents/R/win-library/3.0’

(as ‘lib’ is unspecified)

trying URL 'http://cran.rstudio.com/bin/windows/contrib/3.0/rootSolve_1.6.5.1.zip'

Content type 'application/zip' length 646131 bytes (630 Kb)

opened URL

downloaded 630 Kb

package ‘rootSolve’ successfully unpacked and MD5 sums checked

The downloaded binary packages are in

C:\Users\GIC 76\AppData\Local\Temp\RtmpOmrd7B\downloaded_packages

> library(rootSolve)

Warning message:

package ‘rootSolve’ was built under R version 3.0.3

> fun (All curve(fun(x), -10, 10)

> abline(h=0, col=2)

> (All Sys.info()

sysname release version nodename machine login

"Windows" "7 x64" "build 7601, Service Pack 1" "GIC76-HP" "x86-64" "ivan.gonzalez"

user effective_user

"ivan.gonzalez" "ivan.gonzalez"

> sessionInfo()

R version 3.0.1 (2013-05-16)

Platform: x86_64-w64-mingw32/x64 (64-bit)

locale:

[1] LC_COLLATE=Spanish_Colombia.1252 LC_CTYPE=Spanish_Colombia.1252 LC_MONETARY=Spanish_Colombia.1252 LC_NUMERIC=C LC_TIME=Spanish_Colombia.1252

attached base packages:

[1] stats graphics grDevices utils datasets methods base

other attached packages:

[1] rootSolve_1.6.5.1

loaded via a namespace (and not attached):

[1] tools_3.0.1

##

Did you see curve of the function?

Do you think the root of that is 15011999?

Hi Seyed,

use uniroot.all instead of multiroot (which is intended to solve a set of (nonlinear) equations).

All

I used both multiroot and uniroot.all in my question, and i know uniroot.all can find the roots, but i can not find them by multiroot!!!

Why does not multiroot work good?

I tried to find the root of the function near zero by wolfram mathematica as follow

FindRoot[Cos(2*x)^3,{x,0}]

but the result was zero (similar starting value), while it is clear in attached file that zero is not a root for this function.

Does anyone have any opinions?