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Student Support Forum: 'Plugging a function into a differential equation' topicStudent Support Forum > General > Archives > "Plugging a function into a differential equation"

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Author Comment/Response
Bill Simpson
10/08/12 6:39pm

Perhaps you can see how to apply this.

In[1]:= b[t_]:=Piecewise[{
{100,0≤t<2},
{0,2≤t<4},
{100,4≤t<4+1/2},
{0,4+1/2≤t<4+3/4},
{100,4+3/4≤t≤4+7/8}
}];
DSolve[{a[t]== -a'[t]b[t]},a[t],t]

Out[2]= {{a[t] ->
E^Piecewise[{
{ComplexInfinity, t <= 0},
{-t/100, 0<t<=2},
{ComplexInfinity, 2<t<=4},
{-t/100, 4<t<=9/2},
{ComplexInfinity, 9/2<t<=19/4},
{-t/100, 19/4<t<=39/8}
},
ComplexInfinity
]*C[1]}
}

That doesn't include any initial conditions, because you didn't include what those might be and because when I tried guessing at a few it didn't seem to give results that I thought you could use.

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Subject (listing for 'Plugging a function into a differential equation')
Author Date Posted
Plugging a function into a differential equation Andrew 10/07/12 7:48pm
Re: Plugging a function into a differential equ... Bill Simpson 10/08/12 6:39pm
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