Miscellaneous¶

Time(expr)¶

measure the time taken by a function

Param expr: any expression

The function Time() evaluates the expression expr and prints the time in seconds needed for the evaluation. The time is printed to the current output stream. The built-in function GetTime() is used for timing.

The result is the “user time” as reported by the OS, not the real (“wall clock”) time. Therefore, any CPU-intensive processes running alongside yacas will not significantly affect the result of Time().

Example

In> Time(N(MathLog(1000),40))
0.34 seconds taken
Out> 6.9077552789821370520539743640530926228033;

See also

GetTime()

SystemCall(str)¶

pass a command to the shell

The command contained in the string str is executed by the underlying operating system. The return value of SystemCall() is True or False according to the exit code of the command.

The SystemCall() function is not allowed in the body of the Secure() command.

In a UNIX environment, the command SystemCall("ls") would print the contents of the current directory:

In> SystemCall("ls")
AUTHORS
COPYING
ChangeLog
... (truncated to save space)
Out> True;

The standard UNIX command test returns success or failure depending on conditions. For example, the following command will check if a directory exists:

In> SystemCall("test -d scripts/")
Out> True;

Check that a file exists:

In> SystemCall("test -f COPYING")
Out> True;
In> SystemCall("test -f nosuchfile.txt")
Out> False;