[Date Index] [Thread Index] [Author Index]

A Bug in Flatten?

• To: mathgroup@smc.vnet.net
• Subject: [mg11111] A Bug in Flatten?
• From: Ersek_Ted%PAX1A@mr.nawcad.navy.mil
• Date: Sun, 22 Feb 1998 14:55:36 -0500

Hi
This is Ted Ersek

I got the info on Flatten, and wanted to see what I can do when I give
it a  third argument.

In[1]:=
Remove[f,g];
?Flatten

"Flatten[list] flattens out nested lists.  Flatten[list, n] flattens to 
level \
n. Flatten[list, n, h] flattens subexpressions with head h."

 -------------------------------------- Examples:
In this case it looks like Flatten removed the two outer layers of (f)
In[2]:=
s1=g[f[f[f[1],f[2]],f[f[3],f[4]]]];
Flatten[s1,2,f]

Out[2]=
g[f[1],f[2],f[3],f[4]]

In this case all layers of (f) are removed. In[3]:=
Flatten[s1,Infinity,f]

Out[3]=
g[1,2,3,4]


In the next examples (f) doesn't appear until the third level. Now
Flatten doesn't see (f) at all.  Should layers of (f) get removed in 
these examples?
In[4]:=
s2=g[g[f[f[f[1],f[2]],f[f[3],f[4]]]]]; Flatten[s2,3,f]

Out[4]=
g[g[f[f[f[1],f[2]],f[f[3],f[4]]]]]

In[5]:=
Flatten[s2,Infinity,f]

Out[5]=
g[g[f[f[f[1],f[2]],f[f[3],f[4]]]]]


Ted Ersek