Re: Re: Bug of Integrate
- To: mathgroup at smc.vnet.net
- Subject: [mg83036] Re: [mg83019] Re: Bug of Integrate
- From: "Misco Viadas" <misvrne at gmail.com>
- Date: Thu, 8 Nov 2007 06:10:16 -0500 (EST)
- References: <fg4dfv$6c3$1@smc.vnet.net> <fg6pse$d44$1@smc.vnet.net>
These are my results:
$Version
5.2 for Microsoft Windows (June 20, 2005)
x[t_]:=a Cos[t];y[t_]:=a Sin[t];
The length of the semicircunference is:
In[]: Integrate[Sqrt[1+(y'[t]/x'[t])^2)]*x'[t],{t,0,Pi}]
Out[]: -a*Pi
The length total is:
In[]: Integrate[Sqrt[1+(y'[t]/x'[t])^2)]*x'[t],{t,0,2Pi}]
Out[]: 2*a*Pi
$Version
6.0 for Microsoft Windows (32-bit) (June 19, 2007)
x[t_]:=a Cos[t];y[t_]:=a Sin[t];
The length of the semicircunference is:
In[]: Integrate[Sqrt[1+(y'[t]/x'[t])^2)]*x'[t],{t,0,Pi}]
Out[]: -a*Pi
The length total is:
In[]: Integrate[Sqrt[1+(y'[t]/x'[t])^2)]*x'[t],{t,0,2Pi}]
Out[]: 0
All my calculations stored in my computer are false?. I have to review
them. It means that 3000 manhours to the sea.