Hi,

I am struggling to find a way to change a term like x to x(t) automatically. If I have something like

Data := x^2

diff(Data, x);

the result is 2x

How can I change this 2x to be 2x(t)?

Thanks,

Baharm31

Hi guys,

I am trying to find x(t) from these two equations:

odeA := m*diff(x(t), t, t) = -m*A*sin(2*Pi*f*t) - k*x(t) + 0.5*q(t)*(N__f*epsilon__0*L*(-2*x(t)/(G^2 - x(t)^2) + 2*(G__1^2 - x(t)^2)*x(t)/(G^2 - x(t)^2)^2)*(G^2 - x(t)^2)/(2*tan(alpha)*(G__1^2 - x(t)^2)) + N__f*epsilon__0*L*(-2*x(t)/(G^2 - x(t)^2) + 2*(G__2^2 - x(t)^2)*x(t)/(G^2 - x(t)^2)^2)*(G^2 - x(t)^2)/(2*tan(alpha)*(G__2^2 - x(t)^2)))/(N__f*epsilon__0*L*ln((G__1^2 - x(t)^2)/(G^2 - x(t)^2))/(2*tan(alpha)) + N__f*epsilon__0*L*ln((G__2^2 - x(t)^2)/(G^2 - x(t)^2))/(2*tan(alpha)) + C__p) - d*diff(x(t), t);

diff(q(t), t) = (q(t)/(N__f*epsilon__0*L*ln((G__1^2 - x(t)^2)/(G^2 - x(t)^2))/(2*tan(alpha)) + N__f*epsilon__0*L*ln((G__2^2 - x(t)^2)/(G^2 - x(t)^2))/(2*tan(alpha)) + C__p) + V__bias)/R1


 

How can I use dsolve to find x(t), apart from q(t) all other parameters are constant.

Thanks,

Baharm31

Hi,

Is there anyway to solve this equation for x(t) analytically in Maple?

m * diff(diff(x(t),t), t) = - m * A * sin(2*pi*f*t) - piecewise( abs(x) < x__max, 0, abs(x) >= x__max, -k*(abs(x)-x__max)*Sgn(x)) - diff(x(t), t);

m, x_max, f, A, and k are constant parameters.

Thanks,

Baharm31

Hi,

I am trying to find p and q from this simultaneous equation as a function of system parameters. I do not know the parameters and I need an expression. But Maple simply just gives p=0 and q=0 as an answer

Eq1:=61*q*L__1^2*C*e*eta/(16*omega__n^2)+5*q*L__1^2*C*e^3*eta^3/(8*omega__n^4)+3*C*p^3*gamma__1*(1/4)+3*q*C*p^2*R__n/(4*omega__n)+q*L__1^2*C*e^4*eta^4/(16*omega__n^5)+145*q*L__1^2*C/(64*omega__n)+3*q^3*C*R__n/(4*omega__n)+3*p*C*q^2*gamma__1*(1/4)+q*R*C/(4*omega__n)+19*q*L__1^2*C*e^2*eta^2/(8*omega__n^3):
Eq2:=-3*C*p^3*R__n/(4*omega__n)-3*p*C*q^2*R__n/(4*omega__n)-p*L__1^2*C*e^4*eta^4/(16*omega__n^5)-5*p*L__1^2*C*e^3*eta^3/(8*omega__n^4)-19*p*L__1^2*C*e^2*eta^2/(8*omega__n^3)-61*p*L__1^2*C*e*eta/(16*omega__n^2)-145*p*L__1^2*C/(64*omega__n)-p*R*C/(4*omega__n)+3*q*C*p^2*gamma__1*(1/4)+3*q^3*C*gamma__1*(1/4):
sys := { Eq1 , Eq2 };solve( sys, {p,q} );

Is there any way to help Maple to try other conditions, I know the only solution should not be just p=0 and q=0.

Thanks,

Baharm31

Hi,

I have an expression and want to find its derivative respect to T[1] but not T[2], for example: 

u[1](T[1], T[2], T[3]):=exp(T[1]*I)

If I find the 

diff(u[1](T[1], T[2], T[3]), T[1], T[2])

I would like to get something like this:

D__1*diff(u[1](T[1], T[2], T[3]), T[1])

instead of the derivative respect to T[2], which makes the result to be zero.

I need an expression that I can do other things with it.

You might say why do you just remove the diff of T[2], well I want to automate my code and this is part of the expression so I cannot write something else.

Regards,

Bahar