From: Peter Stephenson <p.stephenson@samsung.com>
To: zsh-workers@zsh.org
Subject: Re: Math expression evaluation error?
Date: Thu, 15 Jan 2015 14:58:45 +0000 [thread overview]
Message-ID: <20150115145845.0e1e7901@pwslap01u.europe.root.pri> (raw)
In-Reply-To: <20150114153842.7b48aa93@pwslap01u.europe.root.pri>
On Wed, 14 Jan 2015 15:38:42 +0000
Peter Stephenson <p.stephenson@samsung.com> wrote:
> I wouldn't have thought so --- I would guess when forcing floating
> point calculations people would expect this to happen everywhere,
> despite what the documentation for the option says.
This notes the change of behaviour.
pws
diff --git a/README b/README
index 4d2b6c1..d2b8b69 100644
--- a/README
+++ b/README
@@ -38,10 +38,12 @@ details, see the documentation.
Incompatibilites between 5.0.7 and 5.0.8
----------------------------------------
-A couple of arithmetic operations have changed: the new behaviour
-is intended to be more consistent, but is not compatible with the old.
+Various arithmetic operations have changed, in particular with respect
+to the choice of integer or floating point operations. The new
+behaviour is intended to be more consistent, but is not compatible with
+the old.
-Previously, the modulus operation, `%', implicitly converted the
+1) Previously, the modulus operation, `%', implicitly converted the
operation to integer and output an integer result, even if one
or both of the arguments were floating point. Now, the C math
library fmod() operator is used to implement the operation where
@@ -57,7 +59,8 @@ New behaviour:
% print $(( 5.5 % 2 ))
1.5
-Previously, assignments to variables assigned the correct type to
+
+2) Previously, assignments to variables assigned the correct type to
variables declared as floating point or integer, but this type was
not propagated to the value of the expression, as a C programmer
would naturally expect. Now, the type of the variable is propagated
@@ -81,6 +84,44 @@ New behaviour:
% print $var
2
+
+3) Previously, the FORCE_FLOAT option only forced the use of floating
+point in arithmetic expressions for integers constants, i.e. numbers
+typed directly into the expression, but not for variables. Hence
+an operation involving only integer variables (or string variables
+containing integers) was not forced to be performed with floating point
+arithmetic. Now, operations involving variables are also forced to
+floating point. For example:
+
+Old behaviour:
+
+% unsetopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0
+% integer i=1 j=2
+% print $(( i / j ))
+0
+% setopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0.5
+% print $(( i / j ))
+0
+
+New behaviour:
+
+% unsetopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0
+% integer i=1 j=2
+% print $(( i / j ))
+0
+% setopt FORCE_FLOAT
+% print $(( 1 / 2 ))
+0.5
+% print $(( i / j ))
+0.5
+
+
Incompatibilities between 5.0.2 and 5.0.5
-----------------------------------------
prev parent reply other threads:[~2015-01-15 14:59 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-09 19:46 jdh
2015-01-09 20:15 ` Peter Stephenson
2015-01-09 21:40 ` jdh
2015-01-09 22:19 ` Ray Andrews
2015-01-09 23:06 ` Lawrence Velázquez
2015-01-09 23:52 ` Ray Andrews
2015-01-10 0:25 ` Bart Schaefer
2015-01-10 7:27 ` Ray Andrews
2015-01-10 16:53 ` Bart Schaefer
2015-01-10 18:48 ` Ray Andrews
2015-01-10 19:14 ` Bart Schaefer
2015-01-10 22:21 ` Ray Andrews
2015-01-11 1:51 ` Bart Schaefer
2015-01-11 5:10 ` Ray Andrews
2015-01-12 9:17 ` Vincent Lefevre
2015-01-12 16:18 ` ZyX
2015-01-13 16:00 ` Vincent Lefevre
2015-01-13 23:03 ` ZyX
2015-01-14 14:47 ` Vincent Lefevre
2015-01-14 21:37 ` ZyX
2015-01-15 13:34 ` Vincent Lefevre
2015-01-15 13:41 ` Vincent Lefevre
2015-01-15 18:32 ` ZyX
2015-01-15 21:57 ` Bart Schaefer
2015-01-09 22:40 ` Peter Stephenson
2015-01-12 10:55 ` Peter Stephenson
2015-01-14 15:02 ` Vincent Lefevre
2015-01-14 15:38 ` Peter Stephenson
2015-01-15 14:58 ` Peter Stephenson [this message]
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