90 Reputation

5 years, 347 days

Finding 4-vector velocity in different m...

Maple

Hello guys,

Assume we have metric ds^2=a(r,t)*dt^2-b(r,t)*dr^2-r^2*dtheta^2-r^2*sin^2(theta)*dphi^2 wherein a(r,t) and b(r,t) are two arbitrary metric functions. how we can find 4-vector velocity for comoving and independent observers?

with best

Covariant Derivative of Riemann, Ricci a...

Maple

hi guys,

suppose we have general metric form in 4-D. I want to calculate Covariant derivative of Riemann, Ricci and Weyl tensors.

with best,

Plot inequality system...

Maple 2021

Hi guys,

I know how to plot inequality system through using with(plots) and inequal term. however, I couldn't plot following system of inqulity equations:

alpha <= 0.0002500000000*(-18000.*m^2 + 47271.*m + 39514. + sqrt(3.24000000*10^8*m^4 - 1.701756000*10^9*m^3 - 4.266980559*10^9*m^2 - 3.036299412*10^9*m - 6.95987804*10^8))/(9.*m^2 + 12.*m + 4.), 0.00005000000000*(-90000.*m^2 + 237237.*m + 198158. + sqrt(8.100000000*10^9*m^4 - 4.270266000*10^10*m^3 - 1.069976858*10^11*m^2 - 7.612670111*10^10*m - 1.744924704*10^10))/(9.*m^2 + 12.*m + 4.) <= alpha, -0.6666666667 < m, m < -0.6665522013

please let me know how we can plot it.

with best

contravariant derivative of contravarian...

Maple

Hi guys,

suppose we have metric in curve geometry such as ds2=A(r)*dt^2-B(r)*dr^2+r^2*dtheta^2+r^2*sin^2(theta)*dphi^2.

how we can calculate and find exact not symbolic different components of contravariant derivative of contravariant derivative of Weyl tensor and Riemann tensor.

with best regards,

exact solution of differential equation...

Maple

Hello guys,

I want to find exact form of a(t) in following differential equation:

-diff(a(t), t)^2*_C1*6^(-1/(-1 + 2*alpha))*((diff(a(t), t, t)*a(t) + diff(a(t), t)^2)/a(t)^2)^(-1/(-1 + 2*alpha))/(4*(diff(a(t), t, t)*a(t) + diff(a(t), t)^2)*(-1/2 + alpha)) = (6*diff(a(t), t, t)*a(t)^2*alpha + 6*a(t)*diff(a(t), t)^2*alpha + k^2)/a(t)^3