Dkunb

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These are questions asked by Dkunb


 

restart;

assume(alpha>0)

assume(delta:: real)

assume(C>0)

 

f:= g->e^(-1/2*(C*g*(1-g^2))^2*(1+delta^2)-C*g*(1-g^2)*alpha)/(g*(1-g^2));

proc (g) options operator, arrow; e^(-(1/2)*C^2*g^2*(1-g^2)^2*(delta^2+1)-C*g*(1-g^2)*alpha)/(g*(1-g^2)) end proc

(1)

convert(1/(g*(1-g^2)),parfrac,g);

-(1/2)/(g+1)+1/g-(1/2)/(g-1)

(2)

f1:= g->-e^(-1/2*(C*g*(1-g^2))^2*(1+delta^2)-C*g*(1-g^2)*alpha)/(2*(g+1));

proc (g) options operator, arrow; -e^(-(1/2)*C^2*g^2*(1-g^2)^2*(delta^2+1)-C*g*(1-g^2)*alpha)/(2*g+2) end proc

(3)

f2 := g->e^(-1/2*(C*g*(1-g^2))^2*(1+delta^2)-C*g*(1-g^2)*alpha)/g;

proc (g) options operator, arrow; e^(-(1/2)*C^2*g^2*(1-g^2)^2*(delta^2+1)-C*g*(1-g^2)*alpha)/g end proc

(4)

f3:= g->-e^(-1/2*(C*g*(1-g^2))^2*(1+delta^2)-C*g*(1-g^2)*alpha)/(2*(g-1));

proc (g) options operator, arrow; -e^(-(1/2)*C^2*g^2*(1-g^2)^2*(delta^2+1)-C*g*(1-g^2)*alpha)/(2*g-2) end proc

(5)

int(f1(g),g=0..infinity);

int(-e^(-(1/2)*C^2*g^2*(-g^2+1)^2*(delta^2+1)-C*g*(-g^2+1)*alpha)/(2*g+2), g = 0 .. infinity)

(6)

 


 

Download 2022_integralIandJ.mw

I do not know why eq(6) does not evaluate. Could you help me?

I have the following warnings. Could you help me fix the problem?

restart;

deS:=diff(x(t),t)=-0.5*x(t)*y(t)

diff(x(t), t) = -.5*x(t)*y(t)

(1)

deI:=diff(y(t),t)=0.5*x(t)*y(t)-0.15*y(t)

diff(y(t), t) = .5*x(t)*y(t)-.15*y(t)

(2)

with(DEtools):

DEplot([deS,deI],[x(t),y(t)],t=0..40,x=0..1,y=0..0.6,[[x(0)=0.99,y(0)=0]])

Warning, plot may be incomplete, the following errors(s) were issued:
   incorrect number of arguments, got 51, expected 50

 

 

 

 

Download DEtools_example.mw

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