Accuracy test for particles in constant electric and magnetic fields

Input files:

setup

NFS=1
output_node_0=0
output_filename=/tmp/const_e
derivative_type=2
field_type=10
num_fieldlines=10
NZ=1
NX=1
NY=1
nits=40000
lenx=10000
leny=10000
lenz=10000
dt=0.000025
racc=1e-9
Det_t=50.0e0
dbob=0.0
b0=1.0
num_integers=0
num_doubles=0

data
 1 5374.35055 5049.64769 9430.07648 10.00000 0.00000 0.00000
 2 6708.08852 8934.84235 8485.36849 10.00000 0.00000 0.00000
 3 6705.08146 3522.59099 1262.11137 10.00000 0.00000 0.00000
 4 6304.60560 7894.47546 6953.63700 10.00000 0.00000 0.00000
 5 9241.32407 2839.61296 5638.50522 10.00000 0.00000 0.00000
 6 4464.51187 3230.59261 2306.51736 10.00000 0.00000 0.00000
 7 1873.51763 2888.45748 9100.62611 10.00000 0.00000 0.00000
 8 6482.95939 4790.61276 1300.24582 10.00000 0.00000 0.00000
 9 7030.68912 6030.61140 2445.67528 10.00000 0.00000 0.00000
10 7868.83354 5828.88246 4226.56298 10.00000 0.00000 0.00000

integer_values

double_values
 

Sample of output files:

const_e1
    uncompressed format (5.95 MB)
    winzip format (1.95 MB)
    gzip format (1.92 MB)

const_e2
    uncompressed format (5.95 MB)
    winzip format (1.95 MB)
    gzip format (1.93 MB)

Accuracy analysis:

Plot between log10 of relative error and t (unit of gyro period)

Explanation of graph:

    The graph shows the relationship log10 of relative error and time for four different values of  racc.

    Slope from these graphs agree with slopes from the graphs in test1.  In this case we also notice that the error oscillates a bit, and the other important difference is the introduction of round off effects for racc = 10-15.