# Numeric#step

**URL:** <https://www.ruby-forum.com/t/numeric-step/98683>\
**Category:** Development\
**Created:** [July 17, 2006, 2:46pm UTC](https://www.ruby-forum.com/t/numeric-step/98683 "2006-07-17T14:46:39Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Tadayoshi\_F](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/2bfe46/32.png) [@Tadayoshi\_F](https://www.ruby-forum.com/u/Tadayoshi_F)\
**Post date:** [July 17, 2006, 2:46pm UTC](https://www.ruby-forum.com/t/numeric-step/98683/1 "2006-07-17T14:46:39Z")

</div>

e$B$U$J$P$G$9!#e(B

Numeric#step e$B$G$9$,!“e(B1.0/0 = e$BL58BBg$G$”$k$H$-!"e(B

$ ruby -v -eInf=1.0/0 -e’1.step(Inf, Inf){|x| p x}’  
ruby 1.8.4 (2005-12-24) [i386-freebsd5.4]

$ ruby -v -r bigdecimal -r bigdecimal/util -eInf=1.0/0  
-e"‘1’.to\_d.step(Inf, Inf){|x| p x}"  
ruby 1.8.4 (2005-12-24) [i386-freebsd5.4]

e$B\>e$N$U$?$D$N\>l9g$O!"D\>$A$K=\*N;$7$^$9$,!"e(B

$ ruby -v -r bigdecimal -r bigdecimal/util -eInf=1.0/0  
-e"‘1’.to\_d.step(Inf.to\_d, Inf.to\_d){|x| p x}"

e$B$3$N\>l9g$O=\*N;$9$kMM;R$,$"$j$^$;$s!#7k2L$,$^$k$G0c$$$^$9$,!"K\>$^$7$$?6e(B  
e$BIq$$$H$O$I$&$$$&$b$N$G$7$g$&$+!#e(B

e$B$^$?!"e(B

$ ruby -v -eInf=1.0/0 -e’10.step(1, Inf){|x| p x}’  
ruby 1.8.4 (2005-12-24) [i386-freebsd5.4]  
NaN

e$B\>e$N$h$&$J\>l9g$O!"e(BNaN e$B$r0lEY0u;z$7$^$9$,!"e(B

$ ruby -v -r bigdecimal -r bigdecimal/util -eInf=1.0/0  
-e"‘10’.to\_d.step(1, Inf.to\_d){|x| p x}"  
ruby 1.8.4 (2005-12-24) [i386-freebsd5.4]

e$B$3$A$i$OD\>$A$K=\*N;$7$^$9!#e(B

---

<div class="post-metadata">

**Author:** ![Tadayoshi\_F](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/2bfe46/32.png) [@Tadayoshi\_F](https://www.ruby-forum.com/u/Tadayoshi_F)\
**Post date:** [July 18, 2006, 3:12pm UTC](https://www.ruby-forum.com/t/numeric-step/98683/2 "2006-07-18T15:12:34Z")

</div>

|From: Tadayoshi F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
|Date: Mon, 17 Jul 2006 21:44:58 +0900

> Numeric#step e$B$G$9$,!“e(B1.0/0 = e$BL58BBg$G$”$k$H$-!"e(B
> 
> $ ruby -v -eInf=1.0/0 -e’1.step(Inf, Inf){|x| p x}’  
> ruby 1.8.4 (2005-12-24) [i386-freebsd5.4]

> $ ruby -v -eInf=1.0/0 -e’10.step(1, Inf){|x| p x}’  
> ruby 1.8.4 (2005-12-24) [i386-freebsd5.4]  
> NaN

e$BK\>$^$7$$?6Iq$$$,$I$&$$$&$b$N$+$O$o$+$j$^$;$s$,!"e(B  
Floate$B$N\>l9g$Ke(BNaNe$B$,=P$k$N$O$^$:$=$&$J$N$G!"e(B  
e$B0J2\<$N$h$&$JBP=h$r9M$($^$7$?!#e(B  
e$B$D$$$G$K%k!\<%W%+%&%s%?$,0n$l$k\>l9g$NBP=h$b$7$F$$$^$9!#e(B  
e$B7Y9p$r=P$9$+$I$&$+e(B/e$B=P$7J}$O$3$l$G$h$$$+$o$+$j$^$;$s$,!#e(B

e$BEDCf\>;9(e(B

— numeric.c~ 2006-05-01 12:46:46 +0900  
+++ numeric.c 2006-07-18 21:05:38 +0900  
@@ -1478,22 +1478,38 @@  
else if (TYPE(from) == T\_FLOAT || TYPE(to) == T\_FLOAT || TYPE(step)  
== T\_FLOAT) {  
const double epsilon = DBL\_EPSILON;  
double beg = NUM2DBL(from);  
double end = NUM2DBL(to);  
double unit = NUM2DBL(step);  
double n = (end - beg)/unit;  
double err = (fabs(beg) + fabs(end) + fabs(end-beg)) / fabs(unit) \*  
epsilon;  
long i;

- int warn = 0;

- if (isinf(beg) || isinf(unit)) {

- 

```
  if ((unit>0 && (end-beg)>=0) || (unit<0 && (end-beg)<=0)) {

```

- 

```
      unit = 0;

```

- 

```
      n = 0;

```

- 

```
  } else {

```

- 

```
      n = -1;

```

- 

```
  }

```

- 

```
  err = 0;

```

- }  
if (err\>0.5) err=0.5;  
n = floor(n + err) + 1;

- if (n\>LONG\_MAX) {

- 

```
  n = LONG_MAX;

```

- 

```
  warn = 1;

```

- }  
for (i=0; i\<n; i++) {  
rb\_yield(rb\_float\_new(i\*unit+beg));  
}

- if (warn)

- 

```
  rb_warn("iteration is reduced to LONG_MAX times");

```

}  
else {  
VALUE i = from;  
ID cmp;

if (RTEST(rb\_funcall(step, ‘\>’, 1, INT2FIX(0)))) {  
cmp = ‘\>’;  
}

- ChangeLog

- e$BJQ99A0F0:ne(B

$ ./ruby -v  
ruby 1.8.5 (2006-07-18) [i686-linux]  
$ ./ruby -e’Inf=1.0/0; 1.step(Inf,1){|x| p x; break if x.abs\>5}’  
1.0  
2.0  
3.0  
4.0  
5.0  
6.0  
$ ./ruby -e’Inf=1.0/0; 1.step(Inf,-1){|x| p x; break if x.abs\>5}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,1){|x| p x; break if x.abs\>5}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,-1){|x| p x; break if x.abs\>5}’  
1.0  
0.0  
-1.0  
-2.0  
-3.0  
-4.0  
-5.0  
-6.0  
$ ./ruby -e’Inf=1.0/0;i=0; Inf.step(1,-1){|x| p x; break if (i+=1)\>5}’  
Infinity  
Infinity  
Infinity  
Infinity  
Infinity  
Infinity  
$ ./ruby -e’Inf=1.0/0;i=0; Inf.step(1,1){|x| p x; break if (i+=1)\>5}’  
$ ./ruby -e’Inf=1.0/0;i=0; (-Inf).step(1,-1){|x| p x; break if  
(i+=1)\>5}’  
$ ./ruby -e’Inf=1.0/0;i=0; (-Inf).step(1,1){|x| p x; break if (i+=1)\>5}’  
-Infinity  
-Infinity  
-Infinity  
-Infinity  
-Infinity  
-Infinity  
$ ./ruby -e’Inf=1.0/0; 1.step(10,Inf){|x| p x}’  
NaN  
$ ./ruby -e’Inf=1.0/0; 1.step(-10,Inf){|x| p x}’  
NaN  
$ ./ruby -e’Inf=1.0/0; 1.step(10,-Inf){|x| p x}’  
NaN  
$ ./ruby -e’Inf=1.0/0; 1.step(-10,-Inf){|x| p x}’  
NaN  
$ ./ruby -e’Inf=1.0/0; 1.step(1,Inf){|x| p x}’  
NaN  
$ ./ruby -e’Inf=1.0/0; 1.step(1,-Inf){|x| p x}’  
NaN  
$ ./ruby -e’Inf=1.0/0; 1.step(Inf,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; 1.step(Inf,-Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,-Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; Inf.step(Inf,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; Inf.step(-Inf,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; Inf.step(Inf,-Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; Inf.step(-Inf,-Inf){|x| p x}’

- e$BJQ998eF0:ne(B

$ ./ruby -e’Inf=1.0/0; 1.step(Inf,1){|x| p x; break if x.abs\>5}‘1.0  
2.0  
3.0  
4.0  
5.0  
6.0  
$ ./ruby -e’Inf=1.0/0; 1.step(Inf,-1){|x| p x; break if x.abs\>5}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,1){|x| p x; break if x.abs\>5}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,-1){|x| p x; break if x.abs\>5}’  
1.0  
0.0  
-1.0  
-2.0  
-3.0  
-4.0  
-5.0  
-6.0  
$ ./ruby -e’Inf=1.0/0;i=0; Inf.step(1,-1){|x| p x; break if (i+=1)\>5}’  
Infinity  
$ ./ruby -e’Inf=1.0/0;i=0; Inf.step(1,1){|x| p x; break if (i+=1)\>5}’  
$ ./ruby -e’Inf=1.0/0;i=0; (-Inf).step(1,-1){|x| p x; break if  
(i+=1)\>5}’  
$ ./ruby -e’Inf=1.0/0;i=0; (-Inf).step(1,1){|x| p x; break if (i+=1)\>5}’  
-Infinity  
$ ./ruby -e’Inf=1.0/0; 1.step(10,Inf){|x| p x}’  
1.0  
$ ./ruby -e’Inf=1.0/0; 1.step(-10,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; 1.step(10,-Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-10,-Inf){|x| p x}’  
1.0  
$ ./ruby -e’Inf=1.0/0; 1.step(1,Inf){|x| p x}’  
1.0  
$ ./ruby -e’Inf=1.0/0; 1.step(1,-Inf){|x| p x}’  
1.0  
$ ./ruby -e’Inf=1.0/0; 1.step(Inf,Inf){|x| p x}’  
1.0  
$ ./ruby -e’Inf=1.0/0; 1.step(Inf,-Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; 1.step(-Inf,-Inf){|x| p x}’  
1.0  
$ ./ruby -e’Inf=1.0/0; Inf.step(Inf,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; Inf.step(-Inf,Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; Inf.step(Inf,-Inf){|x| p x}’  
$ ./ruby -e’Inf=1.0/0; Inf.step(-Inf,-Inf){|x| p x}’  
Infinity