yacas(Ryacas)
yacas()所属R语言包：Ryacas
yacas interface
与yacas接口
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Interface to the yacas computer algebra system.
与yacas计算机代数系统的接口。
用法----------Usage----------
## S3 method for class 'character'
yacas(x, verbose = FALSE, method,
retclass = c("expression", "character", "unquote"), addSemi = TRUE, ...)
## S3 method for class 'expression'
yacas(x, ...)
## S3 method for class 'function'
yacas(x, ...)
## S3 method for class 'formula'[类formula的方法]
yacas(x, ...)
## S3 method for class 'yacas'
yacas(x, ...)
参数----------Arguments----------
参数：x
A yacas character string or an R expression without terminating semicolon to be processed by yacas.
一个与yacas的字符串或R表达没有终止分号来处理与yacas。
参数：verbose
A logical value indicating verbosity of output or "input" to only show input to yacas but not output from yacas or "output" to only show output from yacas but not input to yacas.
一个逻辑值，表示输出的详细程度或"input"只显示输入的与yacas，但不输出与yacas或"output"，只显示输出，从与yacas但没有输入与yacas。
参数：method
method used to communicate with yacas. If "socket" is specified then the same yacas session is used on a sequence of calls. If "system" is specified then a new instance of yacas is used just for the period of that call. "system" does not require that the system be configured to support telnet/sockets and so may be useful in some instances. If no value is specified the default is taken from getOption("yacas.method") and if that is not specified "socket" is used. "socket" and "system" may be abbreviated.
方法沟通与yacas。如果"socket"指定相同与yacas会议上使用的调用序列。如果"system"指定一个新的实例与yacas只用于该呼叫的时期。 "system"不要求该系统被配置为支持Telnet /插座等在某些情况下可能是有用的。如果没有指定值，默认是从getOption("yacas.method")，如果没有指定使用“插座”。 "socket"和"system"可能是缩写。
参数：addSemi
If TRUE a semicolon is added to the character string sent to yacas. This can be set to FALSE if its known that the character string already has a trailing semicolon. It is ignored if retclass="expression".
如果TRUE分号的字符串添加到发送与yacas的。这可以被置为FALSE如果其已知的字符串已经有一个尾随分号。它被忽略，如果retclass="expression"。
参数：retclass
The class of the first component of the yacas structure. It defaults to "expression" but may be specified as "character" or "unquote". "unquote" is the same as "character" except that if the character string returned would have otherwise had quotes in the first and and last positions then they are stripped.
类的第一成分的与yacas结构。它默认为"expression"但是可以指定为"character"或"unquote"。 "unquote"是一样"character"除，如果返回的字符串，否则会引号中的第一个和最后一个位置，他们被剥夺。
参数：...
Additional arguments ultimately passed down to yacas.character.
额外的参数，最终传递给yacas.character。
Details
详细信息----------Details----------
The user supplies an R expression, an R function name corresponding to a function with a single line body, a formula or a yacas input string. In the case of a formula it is regarded as an expression represented by the right hand side of the formula while the left hand side, if any, is ignored.
用户提供一个R的表达，一个R函数名对应的功能与一个单一的线体，公式或一个与yacas的输入字符串。在公式的情况下，它被认为是由下式的右手侧表示的表达式，而在左手侧，如果没有，则忽略。
值----------Value----------
An R object of class "yacas" is returned. If PrettyPrinter("OMForm") is in effect, which it is by default, then the first component is an R expression and the OMForm component contains OpenMath XML code. In other cases the first component is NULL and the YacasForm or PrettyForm components have display information.
一个R对象的的类"yacas"返回。 PrettyPrinter("OMForm")如果效果，默认情况下，它是那么的第一个组件是R的表达和OMForm组件包含OpenMath XML代码。在其他情况下，第一部分是NULL，YacasForm或PrettyForm成分有显示信息。
注意----------Note----------
Windows Installation. On Windows one can install Ryacas by issuing the commands:
Windows安装。在Windows中一个可以安装Ryacas发出命令：
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or by using the Packages | Install package(s) menu in place of the first command. The second command downloads scripts.dat and yacas.exe from the internet and installs them into R_HOME/library/Ryacas/yacdir where R_HOME is the location of your R installation.
或使用Packages | Install package(s)菜单中的第一个命令。第二个命令下载scripts.dat和yacas.exe从互联网上，并把其安装到R_HOME/library/Ryacas/yacdir其中R_HOME是R安装的位置。
Normally the default locations of yacas, its initialization file and the scripts file are sufficient but, if necessary, they can be overridden via the environment variables: YACAS_HOME, YACAS_INIT and YACAS_SCRIPTS. The YACAS_INVOKE_STRING environment variable discussed in the next section overrides all three of these.
通常情况下默认位置与yacas，它的初始化文件和脚本文件是足够的，但是，如果有必要，他们可以通过环境变量覆盖：YACAS_HOME，YACAS_INIT和YACAS_SCRIPTS。 YACAS_INVOKE_STRING环境变量在下一节讨论覆盖了所有这三个。
All OS Installation. The YACAS_INVOKE_STRING environment variable can be used to override the invocation string for yacas. Normally it is not used. If it does need to be used then a typical use might be:
所有的OS安装。 YACAS_INVOKE_STRING环境变量可用于覆盖调用字符串与yacas。它通常不被使用。如果它需要被使用，那么一个典型的使用可能会对
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yacmode. There is also a utility yacmode which is called without arguments and just turns R into a terminal into yacas until one quits out of it (and back to R) by entering stop, end, quit, exit or e.
yacmode。还有一个被称为不带任何参数，只是将R到一个终端到与yacas，直到退出了它（和返回R）进入停止，结束，退出，退出或电子邮件的实用yacmode。
Startup. yacas starts up when yacasStart() is called or the first time yacas is called. yacas is shut down when yacasStop() is called or when the package is detached using the detach() R command. On Windows, when yacas is shut down, the yacas process is terminated on Windows XP Pro but not on other versions of Windows. In those cases there will be a dangling process that the user must terminate manually.
启动。 yacasyacasStart()被称为第一次yacas被称为启动。与yacas被关闭，当yacasStop()被称为或包时，分离detach()使用R命令。在Windows上，与yacas关闭时中，与yacas过程被终止Windows XP专业版，但不能在其他版本的Windows。在这种情况下，会有一个悬空的过程中，用户必须手动终止。
Translation. The translation process occurs in several steps. If the input to the yacas function is an expression then it is translated to a valid yacas character string (otherwise, it is sent to yacas unprocessed). Yacas then processes the string and if retclass="expression" it is translated back to an R expression (otherwise it is sent back unprocessed). Examples of translations are:
翻译。翻译过程中出现的几个步骤。如果输入到yacas函数是一个表达式，然后它被翻译为一个有效的与yacas字符串（否则，它被送到到与yacas未处理）。与yacas处理字符串，如果retclass="expression"它被翻译R的表达（否则它被发送回未加工的）。翻译的例子是：
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参考文献----------References----------
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-9-29 21:11:55
