Hi! I want to compute a partial derivative of the equation (please find it

attached) with respect to the variable x:

ImageShack - Hosting :: diffeqyi0.png

How can i do that with Mathematica? Many thanks

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- Oct 25th 2008, 09:21 AMspicMathematica help - diferential eq
Hi! I want to compute a partial derivative of the equation (please find it

attached) with respect to the variable x:

ImageShack - Hosting :: diffeqyi0.png

How can i do that with Mathematica? Many thanks - Nov 2nd 2008, 06:25 PMHoodI think what you will want to do is to write x as x[t] and
**j**as**j**[t], so the equation would be:

**x''[t]Š1/(M+m Sin[j[t]]^2) *(m Sin[j[t]] (g Cos[j[t]]+ l j'[t]^2)-D x'[t]+F u)**

and to take the partial derivative with respect to x, you would write:**D[x''[t]Š1/(M+m Sin[j[t]]^2) *(m Sin[j[t]] (g Cos[j[t]]+ l j'[t]^2)-D x'[t]+F u),x]**which givesx(3)[t]=(D x''[t])/(M+m Sin[j[t]]2)