Equivalent functions generate different plots
- To: mathgroup at smc.vnet.net
- Subject: [mg26112] Equivalent functions generate different plots
- From: GERMAN <gerbual at col2.telecom.com.co>
- Date: Tue, 28 Nov 2000 01:55:59 -0500 (EST)
- Organization: Universidad Nacional de Colombia
- Sender: owner-wri-mathgroup at wolfram.com
Hi, Group:
With:
In[1]:=
data = {{0, 79.6}, {0.2, 79.2}, {0.4, 77.1}, {0.6, 73.7}, {0.8, 69.1},
{1., 63.2}};
I can to get its cuadratic regression function:
In[2]:=
Fit[data, {1, t, t^2}, t]
Out[2]=
79.68214285714285` + 0.21249999999984936` t - 16.741071428571246` t^2
Then, I can define the regression function in two different, but
equivalent ways:
First: copying and pasting the last output:
In[3]:=
f[t_] :=
79.68214285714285`+ 0.21249999999984936` t - 16.741071428571246 t^2
Second: using directly the *Fit* function in the right hand:
In[4]:=
g[t_] := Fit[data, {1, t, t^2}, t]
In this conditions:
In[5]:=
f[t] == g[t]
Out[5]=
True
However:
In[6]:=
Plot[{f[t], g[t]}, {t, 0, 2.2}]
Out[6]=
(GRAPHICS ...!!!)
genere two different plots (a straight line and a curve). The curve is
well, but the straight line not. I DON'T UNDERSTAND. Can somebody
explain to me this inconsistency?
Thanks in advance.
GERMAN