Measured times on various platforms

The program execution time depends on the number of patches and the number of wire segments used. The central processor time approximately follows the formula;

T=

T₁ + T₂ + T₃+ T₄

T₁=(A₁kN_s² + A₂kN_s² + A₃kN_sN_p + A₄N_c)/M,

T₂=B(N_s + 2N_p)³/M₂,

T₃=CN_s +2N_p)²/M ,

T₄=DkN_f(N_s+2N_p),

where

N_s=number of wire segments,

N_p=number of surface Patches,

N_c=number of connections between a wire and surface,

N_e=number of different excitations,

N_f=number of far-field calculation points

M=number of degrees of symmetry,

k=

1 for structure in free space,

2 for perfect ground of reflection coefficient approximation, and

4 for Sommerfeld/Norton method. T₁ is the time to fill the interaction matrix; T₂ is the time to factor the matrix; T₃ is the time to solve for the currents for all excitations; and T₄ is the time to calculate far fields.

The proportionality factors depend on the computer system on which the program is run. The factors in seconds for a CDC 7600 computer when the matrix fits in core are roughly

A₁=3.(10^-4),

A₂=5.(10^-5),

A₃=5.(10^-4),

A₄=2.(10^-2),

B=2.(10^-6),

C=4.(10^-6), and

D=6.(10^-5), When the extended thin-wire kernel is used, A₁ is increased by about 18 percent. If the approximation for large interaction distances is used with RKH=R_o, then A₁ is multiplied by (1 - 0.7F) where F is the faction of all segment pairs for which the separation is grater than R_o.

Unless a large number of excitations or far fields are requested, T₁ and T₂ will account for nearly all of the running time. If the matrix does not fit in core storage, T₁ and T₂ will be larger than indicated above. They may be much larger if I/O time is included.

The code SOMNEC requires about 15 sec to write the Summerfeld/Norton data file on a CDC 7600 computer.