snapcenter nbody.dat nbody.centered - snapsort nbody.centered nbody.sorted - hackdens nbody.sorted nbody.density -One can also weight the particles by its potential to some power. For this -we create a Plummer sphere, without centering, and compute the center in -two ways:
mkplummer - 100 zerocm=f | snapsort - - rank=r > p.dat - snapcenter p.dat . report=t - hackdens p.dat - | snapcenter - . weight=dens report=t - hackforce p.dat - | snapcenter - . weight="-phi*phi*phi" report=t - hackforce p.dat - | snapcenter - . weight="phi*phi*phi*phi" report=t - -Note that in this case the Plummer sphere should have the correct mathematical +the C.M., and calculate local density. +
snapcenter nbody.dat nbody.centered
+ snapsort nbody.centered nbody.sorted
+ hackdens nbody.sorted nbody.density
+
+
One can also weight the particles by its potential to some power. For +this we create a Plummer sphere, without centering, and compute the center +in two ways: +
mkplummer - 100 zerocm=f | snapsort - - rank=r > p.dat
+ snapcenter p.dat . report=t
+ hackdens p.dat - | snapcenter - . weight=dens report=t
+ hackforce p.dat - | snapcenter - . weight="-phi*phi*phi" report=t
+ hackforce p.dat - | snapcenter - . weight="phi*phi*phi*phi" report=t
+
+ Note that in this case the Plummer sphere should have the correct mathematical
center, and not centered. This snippet of code is expanded in a script $NEMO/scripts/csh/centering.sh,
in which these different methods can also be applied to different models,
-as expanded in the following table.
-
nbody=100 models: Plummer King1 King3 King5 DeVauc - ------------------------------------------------------------- - snapcenter on m: 0.102 0.029* 0.030* 0.033 0.299 - snapcenter on dens: 0.060 0.039 0.036 0.030 0.030* - snapcenter on phi: 0.053 - snapcenter on phi^2: 0.050* - snapcenter on phi^3: 0.052 0.032 0.030 0.026* 0.035 - snapcenter on phi^4: 0.054 0.034 0.032 0.027 0.031 - snapcenterp: 0.080 - snapmnmx on min phi: 0.122 - snapmnmx on m 50% phi: 0.058 - snapmnmx on m 33% phi: 0.063 0.053 - snapmnmx on m 25% phi: 0.067 - rockstart on m: 0.082: -A (*) denotes the best method for that model. -Although for a Plummer sphere the best method is more than twice as good -than the worst method, this does not apply to other models.
+as expanded in the following table. +
nbody=100 models: Plummer
+ King1 King3 King5 DeVauc
+ -------------------------------------------------------------
+ snapcenter on m: 0.102 0.029* 0.030* 0.033 0.299
+ snapcenter on dens: 0.060 0.039 0.036 0.030 0.030*
+ snapcenter on phi: 0.053
+ snapcenter on phi^2: 0.050*
+ snapcenter on phi^3: 0.052 0.032 0.030 0.026* 0.035
+ snapcenter on phi^4: 0.054 0.034 0.032 0.027 0.031
+ snapcenterp: 0.080
+ snapmnmx on min phi: 0.122
+ snapmnmx on m 50% phi: 0.058
+ snapmnmx on m 33% phi: 0.063 0.053
+ snapmnmx on m 25% phi: 0.067
+ rockstart on m: 0.082:
+
+
A (*) denotes the best method for that model. +
+
Although for a Plummer +sphere the best method is more than twice as good than the worst method, +this does not apply to other models.
density(1falcON)
-
-is considerable faster, about twice with their K=32 default.
-
mkplummer - 100000 |is considerable faster, about twice with their K=32 default. - - snapscale - - mscale=10 |about twice with their K=32 default. - snapsort - - |about twice with their K=32 default. - density - - give=mxvr |about twice with their K=32 default. - snapshell - ’10**[-4:4:0.1]’ dens |about twice with their K=32 default. - tabmath - - ’log(%1),log(%4)’ all | - tabplot - 1 2 -4 4 -14 2 line=1,1 point=2,0.1 -vs. -mkplummer - 100000 |line=1,1 point=2,0.1 - snapscale - - mscale=10 | - snapsort - - | - hackdens - - | - snapshell - ’10**[-4:4:0.1]’ dens | - tabmath - - ’log(%1),log(%4)’ all | - tabplot - 1 2 -4 4 -14 2 line=1,1 point=2,0.1 -+ is considerable faster, +about twice with their K=32 default. +
mkplummer - 100000 |\ snapscale - -
+mscale=10 |\
+ snapsort - - |\
+ density - - give=mxvr |\
+ snapshell - ’10**[-4:4:0.1]’ dens |\
+ tabmath - - ’log(%1),log(%4)’ all |\
+ tabplot - 1 2 -4 4 -14 2 line=1,1 point=2,0.1
+
+
vs. +
mkplummer - 100000 |\ snapscale - - mscale=10 |\
+ snapsort - - |\
+ hackdens - - |\
+ snapshell - ’10**[-4:4:0.1]’ dens |\
+ tabmath - - ’log(%1),log(%4)’ all |\
+ tabplot - 1 2 -4 4 -14 2 line=1,1 point=2,0.1
+
+