force floating point arithmetics

force floating point arithmetics

[Stephane Chazelas]

Hiya,

this is a follow up on
http://unix.stackexchange.com/a/66755/22565

I was trying to find a way for $((...)) to always do floating
point arithmetics as in $((1/3)) not returning 0, and the best I
could come up with was appending . to any sequence of decimal
digits that is not otherwise part of a hex number (or number in
another base) or of a variable name or 12e-20 type numbers like:

setopt extendedglob
calc() printf '%.6g\n' $((${*//(#bm)(([0-9.]##[eE][-+][0-9]##|[[:alnum:]_#]#[.#_[:alpha:]][[:alnum:]_#]#)|([0-9]##))/$MATCH${match[3]:+.}}))
alias 'calc=noglob calc'

calc 1/3

...

Like the OP there, I'm surprised there's no easier way to do it,
but maybe I've not looked hard enough.

So, is there a way to force floating point arithmetics there
even when entering integer constants?

Thanks,
Stephane

Re: force floating point arithmetics

[Peter Stephenson]

On Mon, 4 Mar 2013 07:29:02 +0000
Stephane Chazelas <stephane.chazelas@gmail.com> wrote:
> So, is there a way to force floating point arithmetics there
> even when entering integer constants?

I think you'd need something like this.

Works quite well with zcalc, I should probably make it an option.

Index: Doc/Zsh/options.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/options.yo,v
retrieving revision 1.108
diff -p -u -r1.108 options.yo
--- Doc/Zsh/options.yo	15 Nov 2012 21:08:16 -0000	1.108
+++ Doc/Zsh/options.yo	5 Mar 2013 19:50:09 -0000
@@ -485,6 +485,17 @@ Treat the `tt(#)', `tt(~)' and `tt(^)' c
 for filename generation, etc.  (An initial unquoted `tt(~)'
 always produces named directory expansion.)
 )
+pindex(FORCE_FLOAT)
+pindex(NO_FORCE_FLOAT)
+pindex(FORCEFLOAT)
+pindex(NOFORCEFLOAT)
+cindex(floating point, forcing use of)
+cindex(forcing use of floating point)
+item(tt(FORCE_FLOAT))(
+Constants in arithmetic evaluation will be treated as floating point
+even without the use of a decimal point.  Integers in any base
+will be converted.
+)
 pindex(GLOB)
 pindex(NO_GLOB)
 pindex(NOGLOB)
Index: Src/math.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/math.c,v
retrieving revision 1.44
diff -p -u -r1.44 math.c
--- Src/math.c	8 Dec 2012 19:50:34 -0000	1.44
+++ Src/math.c	5 Mar 2013 19:50:09 -0000
@@ -456,6 +456,11 @@ lexconstant(void)
 	    yyval.u.l = zstrtol_underscore(ptr, &ptr, 0, 1);
 	    /* Should we set lastbase here? */
 	    lastbase = 16;
+	    if (isset(FORCEFLOAT))
+	    {
+		yyval.type = MN_FLOAT;
+		yyval.u.d = (double)yyval.u.l;
+	    }
 	    return NUM;
 	}
 	else if (isset(OCTALZEROES))
@@ -475,6 +480,11 @@ lexconstant(void)
 	    {
 		yyval.u.l = zstrtol_underscore(ptr, &ptr, 0, 1);
 		lastbase = 8;
+		if (isset(FORCEFLOAT))
+		{
+		    yyval.type = MN_FLOAT;
+		    yyval.u.d = (double)yyval.u.l;
+		}
 		return NUM;
 	    }
 	    nptr = ptr2;
@@ -537,6 +547,11 @@ lexconstant(void)
 	    lastbase = yyval.u.l;
 	    yyval.u.l = zstrtol_underscore(ptr, &ptr, lastbase, 1);
 	}
+	if (isset(FORCEFLOAT))
+	{
+	    yyval.type = MN_FLOAT;
+	    yyval.u.d = (double)yyval.u.l;
+	}
     }
     return NUM;
 }
Index: Src/options.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/options.c,v
retrieving revision 1.66
diff -p -u -r1.66 options.c
--- Src/options.c	15 Nov 2012 21:08:16 -0000	1.66
+++ Src/options.c	5 Mar 2013 19:50:10 -0000
@@ -131,6 +131,7 @@ static struct optname optns[] = {
 {{NULL, "extendedhistory",    OPT_CSH},			 EXTENDEDHISTORY},
 {{NULL, "evallineno",	      OPT_EMULATE|OPT_ZSH},	 EVALLINENO},
 {{NULL, "flowcontrol",	      OPT_ALL},			 FLOWCONTROL},
+{{NULL, "forcefloat",         0},                        FORCEFLOAT},
 {{NULL, "functionargzero",    OPT_EMULATE|OPT_NONBOURNE},FUNCTIONARGZERO},
 {{NULL, "glob",		      OPT_EMULATE|OPT_ALL},	 GLOBOPT},
 {{NULL, "globalexport",       OPT_EMULATE|OPT_ZSH},	 GLOBALEXPORT},
Index: Src/zsh.h
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/zsh.h,v
retrieving revision 1.187
diff -p -u -r1.187 zsh.h
--- Src/zsh.h	15 Nov 2012 21:08:16 -0000	1.187
+++ Src/zsh.h	5 Mar 2013 19:50:10 -0000
@@ -1988,6 +1988,7 @@ enum {
     EXTENDEDHISTORY,
     EVALLINENO,
     FLOWCONTROL,
+    FORCEFLOAT,
     FUNCTIONARGZERO,
     GLOBOPT,
     GLOBALEXPORT,
Index: Test/C01arith.ztst
===================================================================
RCS file: /cvsroot/zsh/zsh/Test/C01arith.ztst,v
retrieving revision 1.20
diff -p -u -r1.20 C01arith.ztst
--- Test/C01arith.ztst	8 Dec 2012 19:50:37 -0000	1.20
+++ Test/C01arith.ztst	5 Mar 2013 19:50:10 -0000
@@ -243,3 +243,18 @@
 >6000000
 >5000
 >255
+
+  # Force floating point.
+  for expr in "3/4" "0x100/0x200" "0x30/0x10"; do
+    print $(( $expr ))
+    setopt force_float
+    print $(( $expr ))
+    unsetopt force_float
+  done
+0:Forcing floating point constant evaluation, or not.
+>0
+>0.75
+>0
+>0.5
+>3
+>3.

-- 
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/

Re: force floating point arithmetics

[Peter Stephenson]

On Tue, 5 Mar 2013 19:51:47 +0000
Peter Stephenson <p.w.stephenson@ntlworld.com> wrote:
> Works quite well with zcalc, I should probably make it an option.

Index: Doc/Zsh/contrib.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/contrib.yo,v
retrieving revision 1.147
diff -p -u -r1.147 contrib.yo
--- Doc/Zsh/contrib.yo	26 Jan 2013 22:54:01 -0000	1.147
+++ Doc/Zsh/contrib.yo	5 Mar 2013 20:00:42 -0000
@@ -3158,6 +3158,10 @@ The output base can be initialised by pa
 for example `tt(zcalc -#16)' (the `tt(#)' may have to be quoted, depending
 on the globbing options set).
 
+If the option `tt(-f)' is set, all numbers are treated as floating
+point, hence for example the expression `tt(3/4)' evaluates to 0.75
+rather than 0.  Options must appear in separate words.
+
 The prompt is configurable via the parameter tt(ZCALCPROMPT), which
 undergoes standard prompt expansion.  The index of the current entry is
 stored locally in the first element of the array tt(psvar), which can be
Index: Functions/Misc/zcalc
===================================================================
RCS file: /cvsroot/zsh/zsh/Functions/Misc/zcalc,v
retrieving revision 1.20
diff -p -u -r1.20 zcalc
--- Functions/Misc/zcalc	28 Jul 2010 14:01:12 -0000	1.20
+++ Functions/Misc/zcalc	5 Mar 2013 20:00:42 -0000
@@ -114,7 +114,7 @@ float PI E
 (( PI = 4 * atan(1), E = exp(1) ))
 
 # Process command line
-while [[ -n $1 && $1 = -(|[#-]*) ]]; do
+while [[ -n $1 && $1 = -(|[#-]*|f) ]]; do
   optlist=${1[2,-1]}
   shift
   [[ $optlist = (|-) ]] && break
@@ -139,6 +139,9 @@ while [[ -n $1 && $1 = -(|[#-]*) ]]; do
 	    fi
             defbase="[#${arg}]"
 	    ;;
+	(f) # Force floating point operation
+	    setopt forcefloat
+	    ;;
     esac
   done
 done

-- 
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/