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Diffstat (limited to 'doc/expr.n')
| -rw-r--r-- | doc/expr.n | 159 |
1 files changed, 30 insertions, 129 deletions
@@ -1,11 +1,12 @@ '\" '\" Copyright (c) 1993 The Regents of the University of California. '\" Copyright (c) 1994-2000 Sun Microsystems, Inc. +.\" Copyright (c) 2005 by Kevin B. Kenny <kennykb@acm.org>. All rights reserved '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: expr.n,v 1.18 2004/10/27 09:36:58 dkf Exp $ +'\" RCS: @(#) $Id: expr.n,v 1.19 2005/05/10 18:33:59 kennykb Exp $ '\" .so man.macros .TH expr n 8.5 Tcl "Tcl Built-In Commands" @@ -84,8 +85,8 @@ The command will be executed and its result will be used as the operand. .IP [7] As a mathematical function whose arguments have any of the above -forms for operands, such as \fBsin($x)\fR. See below for a list of defined -functions. +forms for operands, such as \fBsin($x)\fR. See MATH FUNCTIONS below for +a discussion of how mathematical functions are handled. .LP Where the above substitutions occur (e.g. inside quoted strings), they are performed by the expression's instructions. @@ -211,131 +212,24 @@ the Tcl parser will evaluate both \fB[a]\fR and \fB[b]\fR before invoking the \fBexpr\fR command. .SS "MATH FUNCTIONS" .PP -Tcl supports the following mathematical functions in expressions, all -of which work solely with floating-point numbers unless otherwise noted: -.DS -.ta 3c 6c 9c -\fBabs\fR \fBcosh\fR \fBlog\fR \fBsqrt\fR -\fBacos\fR \fBdouble\fR \fBlog10\fR \fBsrand\fR -\fBasin\fR \fBexp\fR \fBpow\fR \fBtan\fR -\fBatan\fR \fBfloor\fR \fBrand\fR \fBtanh\fR -\fBatan2\fR \fBfmod\fR \fBround\fR \fBwide\fR -\fBceil\fR \fBhypot\fR \fBsin\fR -\fBcos\fR \fBint\fR \fBsinh\fR -.DE -.PP -.TP -\fBabs(\fIarg\fB)\fR -Returns the absolute value of \fIarg\fR. \fIArg\fR may be either -integer or floating-point, and the result is returned in the same form. -.TP -\fBacos(\fIarg\fB)\fR -Returns the arc cosine of \fIarg\fR, in the range [\fI0\fR,\fIpi\fR] -radians. \fIArg\fR should be in the range [\fI-1\fR,\fI1\fR]. -.TP -\fBasin(\fIarg\fB)\fR -Returns the arc sine of \fIarg\fR, in the range [\fI-pi/2\fR,\fIpi/2\fR] -radians. \fIArg\fR should be in the range [\fI-1\fR,\fI1\fR]. -.TP -\fBatan(\fIarg\fB)\fR -Returns the arc tangent of \fIarg\fR, in the range [\fI-pi/2\fR,\fIpi/2\fR] -radians. -.TP -\fBatan2(\fIy, x\fB)\fR -Returns the arc tangent of \fIy\fR/\fIx\fR, in the range [\fI-pi\fR,\fIpi\fR] -radians. \fIx\fR and \fIy\fR cannot both be 0. If \fIx\fR is greater -than \fI0\fR, this is equivalent to \fBatan(\fIy/x\fB)\fR. -.TP -\fBceil(\fIarg\fB)\fR -Returns the smallest integral floating-point value (i.e. with a zero -fractional part) not less than \fIarg\fR. -.TP -\fBcos(\fIarg\fB)\fR -Returns the cosine of \fIarg\fR, measured in radians. -.TP -\fBcosh(\fIarg\fB)\fR -Returns the hyperbolic cosine of \fIarg\fR. If the result would cause -an overflow, an error is returned. -.TP -\fBdouble(\fIarg\fB)\fR -If \fIarg\fR is a floating-point value, returns \fIarg\fR, otherwise converts -\fIarg\fR to floating-point and returns the converted value. -.TP -\fBexp(\fIarg\fB)\fR -Returns the exponential of \fIarg\fR, defined as \fIe\fR**\fIarg\fR. -If the result would cause an overflow, an error is returned. -.TP -\fBfloor(\fIarg\fB)\fR -Returns the largest integral floating-point value (i.e. with a zero -fractional part) not greater than \fIarg\fR. -.TP -\fBfmod(\fIx, y\fB)\fR -Returns the floating-point remainder of the division of \fIx\fR by -\fIy\fR. If \fIy\fR is 0, an error is returned. -.TP -\fBhypot(\fIx, y\fB)\fR -Computes the length of the hypotenuse of a right-angled triangle -\fBsqrt(\fIx\fR*\fIx\fR+\fIy\fR*\fIy\fB)\fR. -.TP -\fBint(\fIarg\fB)\fR -If \fIarg\fR is an integer value of the same width as the machine -word, returns \fIarg\fR, otherwise -converts \fIarg\fR to an integer (of the same size as a machine word, -i.e. 32-bits on 32-bit systems, and 64-bits on 64-bit systems) by -truncation and returns the converted value. -.TP -\fBlog(\fIarg\fB)\fR -Returns the natural logarithm of \fIarg\fR. \fIArg\fR must be a -positive value. -.TP -\fBlog10(\fIarg\fB)\fR -Returns the base 10 logarithm of \fIarg\fR. \fIArg\fR must be a -positive value. -.TP -\fBpow(\fIx, y\fB)\fR -Computes the value of \fIx\fR raised to the power \fIy\fR. If \fIx\fR -is negative, \fIy\fR must be an integer value. -.TP -\fBrand()\fR -Returns a pseudo-random floating-point value in the range (\fI0\fR,\fI1\fR). -The generator algorithm is a simple linear congruential generator that -is not cryptographically secure. Each result from \fBrand\fR completely -determines all future results from subsequent calls to \fBrand\fR, so -\fBrand\fR 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 \fBsrand\fR function. -.TP -\fBround(\fIarg\fB)\fR -If \fIarg\fR is an integer value, returns \fIarg\fR, otherwise converts -\fIarg\fR to integer by rounding and returns the converted value. -.TP -\fBsin(\fIarg\fB)\fR -Returns the sine of \fIarg\fR, measured in radians. -.TP -\fBsinh(\fIarg\fB)\fR -Returns the hyperbolic sine of \fIarg\fR. If the result would cause -an overflow, an error is returned. -.TP -\fBsqrt(\fIarg\fB)\fR -Returns the square root of \fIarg\fR. \fIArg\fR must be non-negative. -.TP -\fBsrand(\fIarg\fB)\fR -The \fIarg\fR, which must be an integer, is used to reset the seed for -the random number generator of \fBrand\fR. Returns the first random -number (see \fBrand()\fR) from that seed. Each interpreter has its own seed. -.TP -\fBtan(\fIarg\fB)\fR -Returns the tangent of \fIarg\fR, measured in radians. -.TP -\fBtanh(\fIarg\fB)\fR -Returns the hyperbolic tangent of \fIarg\fR. -.TP -\fBwide(\fIarg\fB)\fR -Converts \fIarg\fR to an integer value at least 64-bits wide (by sign-extension -if \fIarg\fR is a 32-bit number) if it is not one already. +When the expression parser encounters a mathematical function +such as \fBsin($x)\fR, it replaces it with a call to an ordinary +Tcl function in the \fBtcl::mathfunc\fR namespace. The processing +of an expression such as: +.CS +\fBexpr {sin($x+$y)}\fR +.CE +is the same in every way as the processing of: +.CS +\fBexpr {[tcl::mathfunc::sin [expr {$x+$y}]]} +.CE +The executor will search for \fBtcl::mathfunc::sin\fR using the +usual rules for resolving functions in namespaces. Either +\fB::tcl::mathfunc::sin\fR or \fB[namespace current]::tcl::mathfunc::sin\fR +will satisfy the request. .PP -In addition to these predefined functions, applications may -define additional functions using \fBTcl_CreateMathFunc\fR(). +See the \fBmathfunc(n)\fR manual page for the math functions that are +available by default. .SS "TYPES, OVERFLOW, AND PRECISION" .PP All internal computations involving integers are done with the C type @@ -430,7 +324,7 @@ each time the expression is executed. Define a procedure that computes an "interesting" mathematical function: .CS -proc calc {x y} { +proc tcl::mathfunc::calc {x y} { \fBexpr\fR { ($x**2 - $y**2) / exp($x**2 + $y**2) } } .CE @@ -470,7 +364,14 @@ set randNum [\fBexpr\fR { int(100 * rand()) }] .CE .SH "SEE ALSO" -array(n), for(n), if(n), string(n), Tcl(n), while(n) +array(n), for(n), if(n), mathfunc(n), namespace(n), proc(n), string(n), Tcl(n), while(n) .SH KEYWORDS arithmetic, boolean, compare, expression, fuzzy comparison + +.SH COPYRIGHT +Copyright (c) 1993 The Regents of the University of California. +.br +Copyright (c) 1994-2000 Sun Microsystems Incorporated. +.br +Copyright (c) 2005 by Kevin B. Kenny <kennykb@acm.org>. All rights reserved. |