RE: Help Formatting Outputs?
- To: mathgroup at smc.vnet.net
- Subject: [mg16977] RE: [mg16966] Help Formatting Outputs?
- From: "Ersek, Ted R" <ErsekTR at navair.navy.mil>
- Date: Sat, 10 Apr 1999 02:13:23 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Daly Gutierrez wrote,
----------------------------
I've been experimenting with formatting results to a desired number
of significant figures. For the most part, I've found PrintPrecision
(in the "Option Inspector" window) quite useful. However, I have a
couple of related questions...
1) How can I display Trailing Zeros?
ex: (253/11.2)*(1/0.62137)*(1/3.8754) = 9.60374 (displaying 6
significant
figures using PrintPrecision). If I change this value to 3, the output
is 9.6 (when in fact I'd like to see 9.60). I've even tried N[%, 3] but
still get 9.6 as a result.
2) Is there a way to display a result in scientific notation WITHOUT
using ScientificForm[expr]? Perhaps using a similar feature in the
"Option Inspector" window? ex: (150/2.2046)*6 = 408.237 (again,
displaying 6 significant figures using PrintPrecision). I would like to
get the same result as ScientificForm[%,1] or 4.x10^2 (in scientific
notation with 1 significant figure). But it would be nice if I could do
it "in the background" so to speak (like changing the number of
significant figures using PrintPrecision).
------------------------------
I don't know of a way to do this that's completely transparent. But you
PaddedForm can be a little helpful. See the lines below.
In[1]:=
x1=PaddedForm[12.3,{4,3}]
Out[1]//PaddedForm=
" 12.300"
In[2]:=
{Head[%],Head[x1]}
Out[2]=
{Real,PaddedForm}
Now isn't that strange! We don't get the same head for (x1) and (%).
If you don't like that you can change $OutputForms using the next line.
In[3]:=
Unprotect[$OutputForms];
$OutputForms=Complement[$OutputForms,{PaddedForm}];
Protect[$OutputForms];
In[4]:=
x2=PaddedForm[13.4,{4,3}]
Out[4]=
" 13.400"
In[5]:=
{Head[%],Head[x2]}
Out[5]=
{PaddedForm,PaddedForm}
Now (x1) and (%) have the same head, and you don't see (PaddedForm) in the
cell label. If you want (x1) and (%) to have the head Real and formatted
with trailing zeros I can't help you. Note that, for positive real numbers
PaddedForm leaves a space where you would get a minus sign for a negative
real number. In spite of the fact that PaddedForm has several options I
can't find a way to prevent this space.
If you use the definitions below for $Post and $Pre PaddedForm will be used
automatically. However, the darn white space before positive numbers
doesn't look good (see the example below).
In[6]:=
$Post=(#/.numb_Real:>
PaddedForm[numb,{1+$PaddedRealDigits,$PaddedRealDigits}])&;
$PaddedRealDigits=3;
$Pre=(#/.PaddedForm[x_Real,_]:>x)&;
In[7]:=
expr=12.3 Sin[8.3 t+2]
Out[7]=
" 12.300" Sin[2+t " 8.300"]
In[8]:=
t=1/2;
expr
Out[8]=
"-1.633"
------------------------
I can't help you with your second question.
I agree it would be nice to have precise control over the way real numbers
are displayed without changing the head of the numbers.
Regards,
Ted Ersek