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guonkon

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I cannot apply this procedure to a bigge...

guonkon 10
August 26 2015
0 0

@Kitonum 

Unfortunately, I cannot apply this procedure to a bigger problem, or at least not straight forward

Example

f:= u*w^3*x*y*z + 3*x^2*y*z;

and I would like to compute the derivative of f with respect to the function w^3 and x^2

df/d(w^3)= u*x*y*z;
df/d(x^2)= 3*y*z;


If I use this procedure I would have to do the following 

 

> 

restart;
> 

with(Student[MultivariateCalculus]):

f:= u*w^3*x*y*z + 3*x^2*y*z;
> 

f:=subs({w^3=wcube,x^2=xsquare},f);
> 

v1:= [1, 0];
v2:= [0, 1];
> 

DirectionalDerivative(f, [wcube,xsquare], v1);
> 

DirectionalDerivative(f, [wcube,xsquare], v2);

u*w^3*x*y*z+3*x^2*y*z

  

u*wcube*x*y*z+3*xsquare*y*z

  

[1, 0]

  

[0, 1]

  

u*x*y*z

  

3*y*z

 (1)

``

Despite that would solve this problem, if my function depends on 32 variables doing this procedure might not be the best approach. But still thank you very much.

Download Example.mw

@Kitonum Thank you very much for yo...

guonkon 10
August 26 2015
0 0

@Kitonum 

Thank you very much for your reply. This example is solved with your suggestion of directional derivative having a vector v:=[0, 1, 0]. I need to verify that I can apply the same procedure for my particular problem. 

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