Provided by: tcl8.5-doc_8.5.19-4_all 
NAME
mathfunc - Mathematical functions for Tcl expressions
SYNOPSIS
package require Tcl 8.5
::tcl::mathfunc::abs arg
::tcl::mathfunc::acos arg
::tcl::mathfunc::asin arg
::tcl::mathfunc::atan arg
::tcl::mathfunc::atan2 y x
::tcl::mathfunc::bool arg
::tcl::mathfunc::ceil arg
::tcl::mathfunc::cos arg
::tcl::mathfunc::cosh arg
::tcl::mathfunc::double arg
::tcl::mathfunc::entier arg │
::tcl::mathfunc::exp arg
::tcl::mathfunc::floor arg
::tcl::mathfunc::fmod x y
::tcl::mathfunc::hypot x y
::tcl::mathfunc::int arg
::tcl::mathfunc::isqrt arg
::tcl::mathfunc::log arg
::tcl::mathfunc::log10 arg
::tcl::mathfunc::max arg ?arg ...?
::tcl::mathfunc::min arg ?arg ...?
::tcl::mathfunc::pow x y
::tcl::mathfunc::rand
::tcl::mathfunc::round arg
::tcl::mathfunc::sin arg
::tcl::mathfunc::sinh arg
::tcl::mathfunc::sqrt arg
::tcl::mathfunc::srand arg
::tcl::mathfunc::tan arg
::tcl::mathfunc::tanh arg
::tcl::mathfunc::wide arg
________________________________________________________________________________________________________________
DESCRIPTION
The expr command handles mathematical functions of the form sin($x) or atan2($y,$x) by converting them to
calls of the form [tcl::mathfunc::sin [expr {$x}]] or [tcl::mathfunc::atan2 [expr {$y}] [expr {$x}]]. A
number of math functions are available by default within the namespace ::tcl::mathfunc; these functions
are also available for code apart from expr, by invoking the given commands directly.
Tcl supports the following mathematical functions in expressions, all of which work solely with floating-
point numbers unless otherwise noted:
abs acos asin atan
atan2 bool ceil cos
cosh double entier exp
floor fmod hypot int
isqrt log log10 max
min pow rand round
sin sinh sqrt srand
tan tanh wide
In addition to these predefined functions, applications may define additional functions by using proc (or
any other method, such as interp alias or Tcl_CreateObjCommand) to define new commands in the
tcl::mathfunc namespace. In addition, an obsolete interface named Tcl_CreateMathFunc() is available to
extensions that are written in C. The latter interface is not recommended for new implementations.
DETAILED DEFINITIONS
abs arg
Returns the absolute value of arg. Arg may be either integer or floating-point, and the result is
returned in the same form.
acos arg
Returns the arc cosine of arg, in the range [0,pi] radians. Arg should be in the range [-1,1].
asin arg
Returns the arc sine of arg, in the range [-pi/2,pi/2] radians. Arg should be in the range
[-1,1].
atan arg
Returns the arc tangent of arg, in the range [-pi/2,pi/2] radians.
atan2 y x
Returns the arc tangent of y/x, in the range [-pi,pi] radians. x and y cannot both be 0. If x is
greater than 0, this is equivalent to “atan [expr {y/x}]”.
bool arg
Accepts any numeric value, or any string acceptable to string is boolean, and returns the
corresponding boolean value 0 or 1. Non-zero numbers are true. Other numbers are false. Non-
numeric strings produce boolean value in agreement with string is true and string is false.
ceil arg
Returns the smallest integral floating-point value (i.e. with a zero fractional part) not less
than arg. The argument may be any numeric value.
cos arg
Returns the cosine of arg, measured in radians.
cosh arg
Returns the hyperbolic cosine of arg. If the result would cause an overflow, an error is
returned.
double arg
The argument may be any numeric value, If arg is a floating-point value, returns arg, otherwise
converts arg to floating-point and returns the converted value. May return Inf or -Inf when the
argument is a numeric value that exceeds the floating-point range.
entier arg
The argument may be any numeric value. The integer part of arg is determined and returned. The │
integer range returned by this function is unlimited, unlike int and wide which truncate their │
range to fit in particular storage widths.
exp arg
Returns the exponential of arg, defined as e**arg. If the result would cause an overflow, an
error is returned.
floor arg
Returns the largest integral floating-point value (i.e. with a zero fractional part) not greater
than arg. The argument may be any numeric value.
fmod x y
Returns the floating-point remainder of the division of x by y. If y is 0, an error is returned.
hypot x y
Computes the length of the hypotenuse of a right-angled triangle “sqrt [expr {x*x+y*y}]”.
int arg
The argument may be any numeric value. The integer part of arg is determined, and then the low
order bits of that integer value up to the machine word size are returned as an integer value.
For reference, the number of bytes in the machine word are stored in tcl_platform(wordSize).
isqrt arg
Computes the integer part of the square root of arg. Arg must be a positive value, either an
integer or a floating point number. Unlike sqrt, which is limited to the precision of a floating
point number, isqrt will return a result of arbitrary precision.
log arg
Returns the natural logarithm of arg. Arg must be a positive value.
log10 arg
Returns the base 10 logarithm of arg. Arg must be a positive value.
max arg ...
Accepts one or more numeric arguments. Returns the one argument with the greatest value.
min arg ...
Accepts one or more numeric arguments. Returns the one argument with the least value.
pow x y
Computes the value of x raised to the power y. If x is negative, y must be an integer value.
rand Returns a pseudo-random floating-point value in the range (0,1). The generator algorithm is a
simple linear congruential generator that is not cryptographically secure. Each result from rand
completely determines all future results from subsequent calls to rand, so rand should not be used
to generate a sequence of secrets, such as one-time passwords. The seed of the generator is
initialized from the internal clock of the machine or may be set with the srand function.
round arg
If arg is an integer value, returns arg, otherwise converts arg to integer by rounding and returns
the converted value.
sin arg
Returns the sine of arg, measured in radians.
sinh arg
Returns the hyperbolic sine of arg. If the result would cause an overflow, an error is returned.
sqrt arg
The argument may be any non-negative numeric value. Returns a floating-point value that is the
square root of arg. May return Inf when the argument is a numeric value that exceeds the square
of the maximum value of the floating-point range.
srand arg
The arg, which must be an integer, is used to reset the seed for the random number generator of
rand. Returns the first random number (see rand) from that seed. Each interpreter has its own
seed.
tan arg
Returns the tangent of arg, measured in radians.
tanh arg
Returns the hyperbolic tangent of arg.
wide arg
The argument may be any numeric value. The integer part of arg is determined, and then the low
order 64 bits of that integer value are returned as an integer value.
SEE ALSO
expr(3tcl), mathop(3tcl), namespace(3tcl)
COPYRIGHT
Copyright (c) 1993 The Regents of the University of California.
Copyright (c) 1994-2000 Sun Microsystems Incorporated.
Copyright (c) 2005, 2006 by Kevin B. Kenny <kennykb@acm.org>.