| % File src/library/base/man/proc.time.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2014 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{proc.time} |
| \alias{proc.time} |
| \alias{print.proc_time} |
| \alias{summary.proc_time} |
| \title{Running Time of R} |
| \description{ |
| \code{proc.time} determines how much real and CPU time (in seconds) |
| the currently running \R process has already taken. |
| } |
| \usage{ |
| proc.time() |
| } |
| \details{ |
| \code{proc.time} returns five elements for backwards compatibility, |
| but its \code{print} method prints a named vector of |
| length 3. The first two entries are the total user and system CPU |
| times of the current \R process and any child processes on which it |
| has waited, and the third entry is the \sQuote{real} elapsed time |
| since the process was started. |
| } |
| \value{ |
| An object of class \code{"proc_time"} which is a numeric vector of |
| length 5, containing the user, system, and total elapsed times for the |
| currently running \R process, and the cumulative sum of user and |
| system times of any child processes spawned by it on which it has |
| waited. (The \code{print} method uses the \code{summary} method to |
| combine the child times with those of the main process.) |
| |
| The definition of \sQuote{user} and \sQuote{system} times is from your |
| OS. Typically it is something like |
| |
| \emph{The \sQuote{user time} is the CPU time charged for the execution |
| of user instructions of the calling process. The \sQuote{system time} |
| is the CPU time charged for execution by the system on behalf of the |
| calling process.} |
| |
| Times of child processes are not available on Windows and will always |
| be given as \code{NA}. |
| |
| The resolution of the times will be system-specific and on Unix-alikes |
| times are rounded down to milliseconds. On modern systems they will |
| be that accurate, but on older systems they might be accurate to 1/100 |
| or 1/60 sec. They are typically available to 10ms on Windows. |
| |
| This is a \link{primitive} function. |
| } |
| |
| \references{ |
| Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) |
| \emph{The New S Language}. |
| Wadsworth & Brooks/Cole. |
| } |
| \seealso{ |
| \code{\link{system.time}} for timing an \R expression, |
| \code{\link{gc.time}} for how much of the time was spent in garbage |
| collection. |
| } |
| \examples{\donttest{ |
| ## a way to time an R expression: system.time is preferred |
| ptm <- proc.time() |
| for (i in 1:50) mad(stats::runif(500)) |
| proc.time() - ptm |
| }} |
| \keyword{utilities} |