# Revision history [back]

### Could s.o. help me with Verifying this system of differential equation

I would like to verify that these functions :

F1=(sqrt(3)sinh(sqrt(3)x)+3sin(x))/(3cos(x)+4-cosh(sqrt(3)*x))

F2=(2sqrt(3)sin((1/2)x)sinh((1/2)sqrt(3)x)+6cos((1/2)x)cosh((1/2)sqrt(3)x))/(3cos(x)+4-cosh(sqrt(3)*x))

G1=(4sqrt(3)cos((1/2)x)sinh((1/2)sqrt(3)x))/(3cos(x)+4-cosh(sqrt(3)x))

G2=(6cos((1/2)x)cosh((1/2)sqrt(3)x)+2sqrt(3)sin((1/2)x)sinh((1/2)sqrt(3)x)+2-2cos(sqrt(3)x))/(3cos(x)+4-cosh(sqrt(3)*x))

are a solution to the system of differential equations:

diff(F1)=F2^2

diff(F2) == F1*F2+G1

diff(G1) == F2*(F2-G2)+F2

diff(G2) == F2*(F1-G1)+G1.

Now, i have tried to solve the system directly with "desolve_system" which obviously didn't work. After that i just differentiated the functions above using sage and hoped that sage could somehow verify that e.g F1'=F2^2 but sadly i couldn't show that this was equal because they had such different forms that sage didn't recognize them as equal. But i know for a fact that these functions satisfy the system of DE. is there any way i could prove this using sage, and if so: how could i do it? and i am looking for an algebraic solution not a numeric one.

I would appreciate any answert to my post

 2 None vdelecroix 7357 ●17 ●81 ●163 http://www.labri.fr/pe...

### Could s.o. help me with Verifying this system of differential equation

I would like to verify that these functions :

F1=(sqrt(3)sinh(sqrt(3)x)+3sin(x))/(3cos(x)+4-cosh(sqrt(3)*x))

F2=(2sqrt(3)sin((1/2)x)sinh((1/2)sqrt(3)x)+6cos((1/2)x)cosh((1/2)sqrt(3)x))/(3cos(x)+4-cosh(sqrt(3)*x))

G1=(4sqrt(3)cos((1/2)x)sinh((1/2)sqrt(3)x))/(3cos(x)+4-cosh(sqrt(3)x))

G2=(6cos((1/2)x)cosh((1/2)sqrt(3)x)+2sqrt(3)sin((1/2)x)sinh((1/2)sqrt(3)x)+2-2cos(sqrt(3)x))/(3cos(x)+4-cosh(sqrt(3)*x))

F1=(sqrt(3)*sinh(sqrt(3)*x)+3*sin(x))/(3*cos(x)+4-cosh(sqrt(3)*x))
F2=(2*sqrt(3)*sin((1/2)*x)*sinh((1/2)*sqrt(3)*x)+6*cos((1/2)*x)*cosh((1/2)*sqrt(3)*x))/(3*cos(x)+4-cosh(sqrt(3)*x))
G1=(4*sqrt(3)*cos((1/2)*x)*sinh((1/2)*sqrt(3)*x))/(3*cos(x)+4-cosh(sqrt(3)*x))
G2=(6*cos((1/2)*x)*cosh((1/2)*sqrt(3)*x)+2*sqrt(3)*sin((1/2)*x)*sinh((1/2)*sqrt(3)*x)+2-2*cos(sqrt(3)*x))/(3*cos(x)+4-cosh(sqrt(3)*x))


are a solution to the system of differential equations:

diff(F1)=F2^2

diff(F1)=F2^2
diff(F2) == F1*F2+G1 F1*F2+G1
diff(G1) == F2*(F2-G2)+F2 F2*(F2-G2)+F2
diff(G2) == F2*(F1-G1)+G1.F2*(F1-G1)+G1.


Now, i have tried to solve the system directly with "desolve_system" which obviously didn't work. After that i just differentiated the functions above using sage and hoped that sage could somehow verify that e.g F1'=F2^2 but sadly i couldn't show that this was equal because they had such different forms that sage didn't recognize them as equal. But i know for a fact that these functions satisfy the system of DE. is there any way i could prove this using sage, and if so: how could i do it? and i am looking for an algebraic solution not a numeric one.

I would appreciate any answert to my post

 3 None vdelecroix 7357 ●17 ●81 ●163 http://www.labri.fr/pe...

### Could s.o. help me with Verifying this system of differential equation

I would like to verify that these functions :

F1=(sqrt(3)*sinh(sqrt(3)*x)+3*sin(x))/(3*cos(x)+4-cosh(sqrt(3)*x))
F2=(2*sqrt(3)*sin((1/2)*x)*sinh((1/2)*sqrt(3)*x)+6*cos((1/2)*x)*cosh((1/2)*sqrt(3)*x))/(3*cos(x)+4-cosh(sqrt(3)*x))
G1=(4*sqrt(3)*cos((1/2)*x)*sinh((1/2)*sqrt(3)*x))/(3*cos(x)+4-cosh(sqrt(3)*x))
G2=(6*cos((1/2)*x)*cosh((1/2)*sqrt(3)*x)+2*sqrt(3)*sin((1/2)*x)*sinh((1/2)*sqrt(3)*x)+2-2*cos(sqrt(3)*x))/(3*cos(x)+4-cosh(sqrt(3)*x))


are a solution to the system of differential equations:

diff(F1)=F2^2
diff(F1) == F2^2
diff(F2) == F1*F2+G1
diff(G1) == F2*(F2-G2)+F2
diff(G2) == F2*(F1-G1)+G1.
F2*(F1-G1)+G1


Now, i have tried to solve the system directly with "desolve_system" which obviously didn't work. After that i just differentiated the functions above using sage and hoped that sage could somehow verify that e.g F1'=F2^2 but sadly i couldn't show that this was equal because they had such different forms that sage didn't recognize them as equal. But i know for a fact that these functions satisfy the system of DE. is there any way i could prove this using sage, and if so: how could i do it? and i am looking for an algebraic solution not a numeric one.

I would appreciate any answert to my post