From: Masahiro TANAKA <masa16.tanaka@...>
Date: 2011-10-02T18:30:06+09:00
Subject: [ruby-core:39828] Re: [Ruby 1.9 - Bug #4576] Range#step miss the last value, if end-exclusive and has float number

2011/9/17 Masahiro TANAKA <masa16.tanaka@gmail.com>:
> --- numeric.c � (revision 33288)
> +++ numeric.c � (working copy)
> @@ -1690,8 +1690,16 @@
> � � � �}
> � � � �else {
> � � � � � �if (err>0.5) err=0.5;
> - � � � � � n = floor(n + err);
> - � � � � � if (!excl || ((long)n)*unit+beg < end) n++;
> + � � � � � if (excl) {
> + � � � � � � � if (n>0) {
> + � � � � � � � � � if (n<err)
> + � � � � � � � � � � � n = 1;
> + � � � � � � � � � else
> + � � � � � � � � � � � n = floor(n - err) + 1;
> + � � � � � � � }
> + � � � � � } else {
> + � � � � � � � n = floor(n + err) + 1;
> + � � � � � }
> � � � � � �for (i=0; i<n; i++) {
> � � � � � � � �rb_yield(DBL2NUM(i*unit+beg));
> � � � � � �}

This patch involves a problem:
 a=(1.0..1-2e-16).step(1.0).to_a; p a #=> [1.0] ; should be []

The following patch would be better.

--- numeric.c	(revision 33377)
+++ numeric.c	(working copy)
@@ -1690,9 +1690,18 @@
 	}
 	else {
 	    if (err>0.5) err=0.5;
-	    n = floor(n + err);
-	    if (!excl || ((long)n)*unit+beg < end) n++;
-	    for (i=0; i<n; i++) {
+	    if (excl) {
+		if (n<=0) return TRUE;
+		if (n<1)
+		    n = 0;
+		else
+		    n = floor(n - err);
+	    }
+	    else {
+		if (n<0) return TRUE;
+		n = floor(n + err);
+	    }
+	    for (i=0; i<=n; i++) {
 		rb_yield(DBL2NUM(i*unit+beg));
 	    }
 	}

Masahiro Tanaka