On Mon, Oct 6, 2008 at 11:28 PM, Alan Bromborsky <[EMAIL PROTECTED]> wrote:
>
> Suppose I have two symbols A and B that I wish to declare implicit
> functions of say the symbols x1, x2, and x3. Then I wish to calculate
> the derivative of A*B with respect to x1 and x2 and x3. Can I do this
> and if so how?
Yes, for example this way:
In [2]: A = Function("A")
In [3]: B = Function("B")
In [4]: var("x1 x2 x3")
Out[4]: (x₁, x₂, x₃)
In [5]: f = A(x1, x2, x3)*B(x1, x2, x3)
In [6]: f
Out[6]: A(x₁, x₂, x₃)⋅B(x₁, x₂, x₃)
In [7]: diff(f, x1)
Out[7]:
d d
A(x₁, x₂, x₃)⋅───(B(x₁, x₂, x₃)) + B(x₁, x₂, x₃)⋅───(A(x₁, x₂, x₃))
dx₁ dx₁
Ondrej
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