| | 1 | == Compare SplinePotential(r,r_soft) with RelativePotential_1(mass,pos,r_soft) == |
| | 2 | |
| | 3 | 1. When r/r_soft > 0.5 SplinePotential |
| | 4 | |
| | 5 | {{{ |
| | 6 | (-16/5+(y^2*(32/3+y*(48/5-32/15*y)))+1/15*y)/r_soft |
| | 7 | }}} |
| | 8 | Or |
| | 9 | |
| | 10 | {{{ |
| | 11 | (-16/5+32/3*y^2 + 48/5*y^3 -32/15*y^4 +1/15*y)/r_soft |
| | 12 | }}} |
| | 13 | |
| | 14 | {{{ |
| | 15 | FUNCTION SplinePotential(r,r_soft) |
| | 16 | REAL(KIND=qPREC) :: r, r_soft,y |
| | 17 | REAL(KIND=qPREC) :: SplinePotential |
| | 18 | REAL(KIND=qPREC), PARAMETER :: & |
| | 19 | GSC0=-14d0/5d0, & |
| | 20 | GSC1=16d0/3d0, & |
| | 21 | GSC2=-48d0/5d0, & |
| | 22 | GSC3=32d0/5d0, & |
| | 23 | GSC4=32d0/3d0, & |
| | 24 | GSC5=-16d0, & |
| | 25 | GSC6=48d0/5d0, & |
| | 26 | GSC7=-32d0/15d0, & |
| | 27 | GSC8=1d0/15d0, & |
| | 28 | GSC9=-16d0/5d0 |
| | 29 | y=r/r_soft |
| | 30 | IF (GravityDim == 3) THEN |
| | 31 | IF (r >= r_soft) THEN |
| | 32 | SplinePotential=-1d0/r |
| | 33 | ELSE |
| | 34 | y=r/r_soft |
| | 35 | IF (r >= half*r_soft) THEN |
| | 36 | SplinePotential=(GSC9+(y**2*(GSC4+y*(GSC5+y*(GSC6+y*GSC7)))+GSC8/y )) / r_soft |
| | 37 | ELSE |
| | 38 | SplinePotential=(GSC0 + (y**2*(GSC1+y**2*(GSC2+y*GSC3)))) / r_soft |
| | 39 | END IF |
| | 40 | END IF |
| | 41 | ELSE |
| | 42 | SplinePotential=PlummerPotential2D(r,r_soft) |
| | 43 | END IF |
| | 44 | END FUNCTION SplinePotential |
| | 45 | |
| | 46 | }}} |
| | 47 | |
| | 48 | 2. When r/r_soft > 0.5 RelativePotential_1(mass,pos,r_soft) See below for the script from Luke |
| | 49 | |
| | 50 | {{{ |
| | 51 | -1/15 - 32/3*y^3 + 16*y^4 - 48/5*y^5 + 32/15 *y^6 + 48/15*y) |
| | 52 | }}} |
| | 53 | |
| | 54 | |
| | 55 | {{{ |
| | 56 | FUNCTION RelativePotential_1(mass,pos,r_soft) |
| | 57 | REAL(KIND=qPREC), DIMENSION(3) :: pos |
| | 58 | REAL(KIND=qPREC) :: RelativePotential_1 |
| | 59 | REAL(KIND=qPREC) :: mass, r_soft, r, r2 |
| | 60 | REAL(KIND=qPREC) :: u_1, phi0_rel_1, spline_A_1, spline_B_1 |
| | 61 | REAL(KIND=qPREC) :: phi_rel_1_A, phi_rel_1_B, phi_rel_1_C |
| | 62 | |
| | 63 | r2=sum(pos(1:nDim)**2) |
| | 64 | r=sqrt(r2) |
| | 65 | |
| | 66 | u_1=r/r_soft |
| | 67 | |
| | 68 | phi0_rel_1=-1d0*mass*ScaleGrav/r |
| | 69 | spline_A_1=-16d0/3d0*u_1**3 + 48d0/5d0*u_1**3 - 32d0/5d0*u_1**6 + 14d0/5d0*u_1 |
| | 70 | spline_B_1=-1d0/15d0 - 32d0/3d0*u_1**3 + 16d0*u_1**4 - 48d0/5d0*u_1**5 + 32d0/15d0*u_1**6 + 48d0/15d0*u_1 |
| | 71 | |
| | 72 | phi_rel_1_A=0d0 |
| | 73 | phi_rel_1_B=0d0 |
| | 74 | phi_rel_1_C=0d0 |
| | 75 | if(u_1<0.5) then |
| | 76 | phi_rel_1_A=phi0_rel_1*spline_A_1 |
| | 77 | else if(u_1>1.0) then |
| | 78 | phi_rel_1_C=phi0_rel_1 |
| | 79 | else |
| | 80 | phi_rel_1_B=phi0_rel_1*spline_B_1 |
| | 81 | end if |
| | 82 | |
| | 83 | RelativePotential_1=(phi_rel_1_A+phi_rel_1_B+phi_rel_1_C) |
| | 84 | |
| | 85 | END FUNCTION RelativePotential_1 |
| | 86 | |
| | 87 | }}} |
| | 88 | |
| | 89 | |
| | 90 | |
| | 91 | |
| | 92 | ======== |