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Can Maple simplify these DE's by eliminating the d/dt VL(t) by taking the derrivative of the bottom equation and substituting in the first one? 

In this question, I asked for a way to simplify an expression containing radicals. The discussion led us to that as default field for simplicfication is the Complex number system we should use assume or assuming command to simplify the radicals. However, the mothod suggested there seems to not work in this new case that I have. For details please see the attached file. The terms sqrt{u} and sqrt{u-1} should cancel in denominator.

 What Maple Does

restart

`ϕ` := (1+sqrt(5))*(1/2)

1/2+(1/2)*5^(1/2)

(1)

f := (1/2)*sqrt(-(u-1)*(u+1)*(u^2-u-1))*u*(4*u-3)/sqrt(u*(u-1))

(1/2)*(-(u-1)*(u+1)*(u^2-u-1))^(1/2)*u*(4*u-3)/(u*(u-1))^(1/2)

(2)

`assuming`([combine(f)], [1 < u and u < `&varphi;`])

(1/2)*u*(4*u-3)*((u+1)*(-u^2+u+1)/u)^(1/2)

(3)

`assuming`([simplify(f)], [1 < u and u < `&varphi;`])

(1/2)*(-u^2+u+1)^(1/2)*(u^2-1)^(1/2)*u^(1/2)*(4*u-3)/(u-1)^(1/2)

(4)

`assuming`([combine(f, radical)], [1 < u and u < `&varphi;`])

(1/2)*u*(4*u-3)*((u+1)*(-u^2+u+1)/u)^(1/2)

(5)

`assuming`([simplify(f, radical)], [1 < u and u < `&varphi;`])

(1/2)*((u-1)*(u+1)*(-u^2+u+1))^(1/2)*u*(4*u-3)/(u*(u-1))^(1/2)

(6)

``

Radical.mw

 Remark by Markiyan Hirnyk. The below content is added by the questionner on 08.02.2016 .

What Mathematica Does

 

I assume that I'm not providing the correct input to the simplify command to get the simplification that I want.  In particular, for the following code:

assume(n, positive);
simplify(3^(-(1/2)*n)*2^((1/6)*n)-2^((2/3)*n)*6^(-(1/2)*n));
simplify(log(3^(-(1/2)*n)*2^((1/6)*n))-log(2^((2/3)*n)*6^(-(1/2)*n))); 

The expression should evaluate to 0.  However, the first expression does not simplify to 0 (it does not simplify at all in Maple) while the second expression simplifies to 0.

The simplification is fairly easy for the first expression by factoring 6 and combining terms; it seems like I'm not entering the command to simplify in this way.

I have the following expression

f=u/(sqrt(u*(u-1)))

and I want to simplify it. Eventhough that I tell Maple that u is real and greater than 1 but it does not simplify the expression. What is wrong? Please see the attached file.

Radical.mw

a1:= f(x) :
> T1 :=simplify((taylor(a1,x=alpha,N+3))):
> E1:=subs([seq(((D@@i)(f))(alpha) = 0,i=1..m-1),f(alpha)=0,x=e[n]+alpha],T1):
> g1 :=(convert(simplify(series((E1,e[n]=0,N))),polynom));

 

This is a stripped down example of something I've been doing. Basically I'm building matrices which I then, using unapply, convert into functions of some variables of t.
.... but found that simplify seems to often not work as i'd wish.
 

restart:
mm:=Matrix([[cos(sqrt(g__1^2)*t), (-I*g__1*sin(sqrt(g__1^2)*t))*(1/sqrt(g__1^2))], [(-I*g__1*sin(sqrt(g__1^2)*t))*(1/sqrt(g__1^2)) ,cos(sqrt(g__1^2)*t)]]);

#great - simplifies as i'd expect:
simplify(mm) assuming g__1::positive;

Do the same thing but when matrix is a function of t
mmFun:=unapply(mm, t);

#the function works - gives what i'd expect
mmFun(3); mmFun(t);

#but now the simplification does not work - why the g__1 in the argument of cos does not get properly simplified?
simplify(mmFun(t)) assuming g__1::positive;

Any ideas if this is a bug? I'm using maple 2015.2 on linux 64-bit.

here is the worksheet: simplify_issue.mw

thanks

EDIT:

as a side note once can sometimes overcome this with mapping simplify  as in :

map(simplify, resultMatrix ) assuming g__1::positive;

but this is not optimal, and sometimes does not work when i first multiply the matrix by say a vector.

 

 

 

Dear all,

Thank you for helping me  to generate a table of values of f(x) starting with x=0 to 100 in steps of 1, that is for x=0,1,2,3,...,100.

 

I tried:

f:=x->2*sqrt(3)*a1*a2*(sum(pochhammer(1/3,k)*3^k*x^(3*k)/(3*k)! ,k=0..infinity)*sum(pochhammer(2/3,k)*3^k*x^(3*k+2)/(3*k+2)!  ,k=0..infinity)-sum(pochhammer(2/3,k)*3^k*x^(3*k+1)/(3*k+1)!  ,k=0..infinity)*sum(pochhammer(1/3,k)*3^k*x^(3*k+1)/(3*k+1)!  ,k=0..infinity));

tab_values:=[evalf(simplify(seq(Ni1(xx),xx=0..100)))];

But I the result is amazing.... I don't understand the problem.

Thanks

 

I have a polynomial expression that I would like to cast into a specific form. The expression is

and I know that it can be simplified into a form involving squares of (A[Qi]-Pi). It is trivial to do this on paper; how can I convince Maple to do this.

The solution I came up with was to use mtaylor and expand about the forms I know to be there:

mtaylor((3),[A[Q1]=P1,A[0]=P2*rho/(rho+Q1),A[Q3]=P3],6);

which is what I want (close to, anyway). Now, I consider this to be a bit of a dirty trick that works here as the expression is simple and no higher-order terms are present so in fact the solution is exact. But, are there methods along simplify and friends that can do this? I have not been successfull with those...

This is a part of a much longer worksheet and part of a lecture, so I need Maple to be able to do this. The mtaylor trick works, but I would not want to miss an obvious approach that may work where mtaylor would get confused.

Thanks,

M.D.

test.mw

I try to find the exact (symbolic) value of

(-2*sqrt(7)-4)*EllipticK((1/8)*sqrt(2)*(-3+sqrt(7)))^2+4*EllipticE(-(1/8)*sqrt(2)*(-3+sqrt(7)))*sqrt(7)*EllipticK((1/8)*sqrt(2)*(-3+sqrt(7)))

I tried 'simplify' with different options and 'convert'. It would be pi=3.141... as numerical approximation suggests.

Many thanks.

It is given 

   xn (n x - n - x) / (x-1)2 + x / (x-1)2  , n is a (symbolic) positive integer.

I want to transform it into

n xn+1 / (x-1) - x (xn-1) / (x-1)2

How is it possible?

I tried the  simplify, convert (parfrac), collect, combine, expand,  with/without assuming.

Thanks in advance.

why is simplify is making errors - me or maple?

Ec := (1/2)*Kc*(2*Pi*h0/Pi(a0^2+h0^2)-2*Pi*h/Pi(a^2+h^2))^2;
2
1 / 2 Pi h0 2 Pi h \
- Kc |------------- - -----------|
2 | / 2 2\ / 2 2\|
\Pi\a0 + h0 / Pi\a + h //
simplify(%);
2
2 Kc (-h0 + h)

 

Simplify is erasing the varibles a0 and a. Is there a secret to using simplify?

 

The two forms below (eqn1 and eqn2) give the same result. You can convert from eqn1 to eqn2 using the expand option but is there a way can you get Maple to simplify eqn2 back to eqn1?

( I have tried all the simplify options I know)

 

eqn1:= int(int(k(upsilon)*h(tau)*x(t-tau)*x(t-upsilon), tau = -infinity .. infinity), upsilon = -infinity .. infinity)

 

eqn2:= (int(h(tau)*x(t-tau), tau = -infinity .. infinity))*(int(k(upsilon)*x(t-upsilon), upsilon = -infinity .. infinity))

 

 

Thanks.

hi,

here a comlicated formula,how i simplify

thanks  a lot.

``

f := (kappa*omega^2+omega^3)*(Y+(-sqrt(N)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+sqrt(N)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)/(2*(kappa*omega^2+omega^3)))^2/(2*omega)+(-kappa*omega^2+omega^3)*(X+(sqrt(N)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+sqrt(N)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)/(2*(-kappa*omega^2+omega^3)))^2/(2*omega)+(Omega*N*cos(theta[2])*omega+Omega*N*cos(theta[1])*omega-P__X^2*kappa+P__X^2*omega+P__Y^2*kappa+P__Y^2*omega)/(2*omega)-(sqrt(N)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+sqrt(N)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)^2/(8*omega*(-kappa*omega^2+omega^3))-(-sqrt(N)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+sqrt(N)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)^2/(8*omega*(kappa*omega^2+omega^3))

(1/2)*(kappa*omega^2+omega^3)*(Y+(-N^(1/2)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+N^(1/2)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)/(2*kappa*omega^2+2*omega^3))^2/omega+(1/2)*(-kappa*omega^2+omega^3)*(X+(N^(1/2)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+N^(1/2)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)/(-2*kappa*omega^2+2*omega^3))^2/omega+(1/2)*(Omega*N*cos(theta[2])*omega+Omega*N*cos(theta[1])*omega-P__X^2*kappa+P__X^2*omega+P__Y^2*kappa+P__Y^2*omega)/omega-(1/8)*(N^(1/2)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+N^(1/2)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)^2/(omega*(-kappa*omega^2+omega^3))-(1/8)*(-N^(1/2)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+N^(1/2)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)^2/(omega*(kappa*omega^2+omega^3))

(1)

``

(1/2)*(kappa*omega^2+omega^3)*(Y+(-N^(1/2)*omega^(3/2)*sin(theta[2])*cos(varphi[2])*lambda__b+N^(1/2)*omega^(3/2)*sin(theta[1])*cos(varphi[1])*lambda__a)/(2*kappa*omega^2+2*omega^3))^2/omega

(2)

``

    f is a complicated function,i want to make it more simplify,but i want to keep square style,

 let coefficients of X and Y keep one unit,and simplify terms  containd special symbol of omega

 

Download Q1119.mw

it what i wanted.

Hello,

 

I am trying to differentiate a matrix containing four variables, alpha, alphaB (representing alpha bar), beta, and betaB (for beta bar). They are are variables with respect to t. I then need to let t=0 and then simplify the result with some initial conitions i have. Could you tell me any useful maple functions which i can use to do this? If you need anymore information let me know and thank you for helping me.

 

Robbie

can someone tell me how can I derive and solve d(g1(x))=0 a complicated function as

I tried with the instructions simplify and combine but without results.

Thanks in advance.

 

 

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