## 25 Reputation

6 years, 324 days

## MaplePrimes Activity

### These are questions asked by Mitterrand

Maple 2015

I wanted to calculate the bessel function's limit, but there is no results.

 (1)

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 (8)

## How to take the rational function apart ...

Maple

The expression is:

sqrt(Dp)*(-Dp*sqrt(s+thetac)*alpha1*pinf*s^2-2*Dp*sqrt(s+thetac)*alpha1*pinf*s*thetac-Dp*sqrt(s+thetac)*alpha1*pinf*thetac^2+A2*Dp*sqrt(s+thetac)*alpha1*s+A2*Dp*sqrt(s+thetac)*alpha1*thetac+Dc*sqrt(s+thetac)*alpha1*pinf*s^2+Dc*sqrt(s+thetac)*alpha1*pinf*s*thetac+A1*Dc*alpha1*s^2+A1*Dc*alpha1*s*thetac+A1*sqrt(Dc)*sqrt(s+thetac)*s^2+A1*sqrt(Dc)*sqrt(s+thetac)*s*thetac-A2*Dc*sqrt(s+thetac)*alpha1*s)*exp((-lh+x)*sqrt(s)/sqrt(Dp))/((s+thetac)^(3/2)*s*(Dc*s-Dp*s-Dp*thetac)*(-sqrt(Dp)*alpha1+sqrt(s)))

## further simplication...

Maple

I have gotten an expression:

eq21 := collect(eq20, [exp(-sqrt(s)*x/sqrt(Dp)), exp(sqrt(s)*(-lh+x)/sqrt(Dp)), exp((-2*lh+x)*sqrt(s)/sqrt(Dp)), exp((lh-x)*sqrt(s+thetac)/sqrt(Dc))], simplify);

q(x, s) = exp(-sqrt(s)*x/sqrt(Dp))*_F1(s)+sqrt(Dp)*(-Dp*sqrt(s+thetac)*alpha1*pinf*s^2-2*Dp*sqrt(s+thetac)*alpha1*pinf*s*thetac-Dp*sqrt(s+thetac)*alpha1*pinf*thetac^2+A2*Dp*sqrt(s+thetac)*alpha1*s+A2*Dp*sqrt(s+thetac)*alpha1*thetac+Dc*sqrt(s+thetac)*alpha1*pinf*s^2+Dc*sqrt(s+thetac)*alpha1*pinf*s*thetac+A1*Dc*alpha1*s^2+A1*Dc*alpha1*s*thetac+A1*sqrt(Dc)*sqrt(s+thetac)*s^2+A1*sqrt(Dc)*sqrt(s+thetac)*s*thetac-A2*Dc*sqrt(s+thetac)*alpha1*s)*exp(sqrt(s)*(-lh+x)/sqrt(Dp))/((s+thetac)^(3/2)*(-sqrt(Dp)*alpha1+sqrt(s))*s*(Dc*s-Dp*s-Dp*thetac))+(sqrt(Dp)*alpha1+sqrt(s))*_F1(s)*exp((-2*lh+x)*sqrt(s)/sqrt(Dp))/(-sqrt(Dp)*alpha1+sqrt(s))+Dc*A1*exp((lh-x)*sqrt(s+thetac)/sqrt(Dc))/((Dc*s-Dp*s-Dp*thetac)*sqrt(s+thetac))-(-pinf*s-pinf*thetac+A2)/((s+thetac)*s)

I need to further simplify the coefficient of

exp(sqrt(s)*(-lh+x)/sqrt(Dp))

Would you like to give some tips?

Thanks.

## How to simplify an expression...

Maple

In this expression,

q(x, s) = -(-(-thetac*s^(3/2)-s^(5/2)+(s^2+s*thetac)*alpha1*sqrt(Dp))*Dc*A1*exp((lh-x)*sqrt(s+thetac)/sqrt(Dc))+((alpha1*(s+thetac)*(-pinf*s-pinf*thetac+A2)*Dp^(3/2)+s*sqrt(Dp)*(A1*(s+thetac)*sqrt(Dc)-Dc*alpha1*(-pinf*s-pinf*thetac+A2)))*sqrt(s+thetac)+A1*sqrt(Dp)*s*Dc*alpha1*(s+thetac))*exp(sqrt(s)*(-lh+x)/sqrt(Dp))-(-_F1(s)*(-s*alpha1*(s+thetac)^2*Dp^(3/2)-s^(3/2)*Dp*thetac^2+thetac*(Dc-2*Dp)*s^(5/2)+(Dc-Dp)*s^(7/2)+sqrt(Dp)*s^2*Dc*alpha1*(s+thetac))*exp((-2*lh+x)*sqrt(s)/sqrt(Dp))+_F1(s)*(-s*alpha1*(s+thetac)^2*Dp^(3/2)-thetac*(Dc-2*Dp)*s^(5/2)+(-Dc+Dp)*s^(7/2)+s^(3/2)*Dp*thetac^2+sqrt(Dp)*s^2*Dc*alpha1*(s+thetac))*exp(-sqrt(s)*x/sqrt(Dp))+alpha1*(s+thetac)*(-pinf*s-pinf*thetac+A2)*Dp^(3/2)+(-pinf*(Dc-2*Dp)*thetac+A2*(Dc-Dp))*s^(3/2)-pinf*(Dc-Dp)*s^(5/2)-s*alpha1*Dc*(-pinf*s-pinf*thetac+A2)*sqrt(Dp)-sqrt(s)*Dp*thetac*(-pinf*thetac+A2))*sqrt(s+thetac))/((s+thetac)^(3/2)*s*((Dc-Dp)*s-Dp*thetac)*(sqrt(Dp)*alpha1-sqrt(s)))

I want to simplify the coeffcients of

exp((lh-x)*sqrt(s+thetac)/sqrt(Dc)), exp(sqrt(s)*(-lh+x)/sqrt(Dp)), exp((-2*lh+x)*sqrt(s)/sqrt(Dp)), exp(-sqrt(s)*x/sqrt(Dp)).

## Is the Inverse Laplace Transform correct...

Maple can calculate one Inverse Laplace Transform and give the result.

But I find this integral diverges because this term exp(alpha1*(Dp*alpha1*t-lh+x)) is infinite in one interval.

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