# numSummationTerms

Change number of summation terms for calculating periodic Green's function

## Description

example

numSummationTerms(array,num) changes the number of summation terms used to calculate periodic Green's function of the infinite array. This method calculates $2*num+1$ of the periodic Green's function. The summation is carried out from –num to +num. A higher number of terms results in better accuracy but increases the overall computation time.

## Input Arguments

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Infinite array, specified as a scalar.

Number to calculate summation terms, specified as a scalar. The summation is carried out from –num to +num.

Example: 50

## Examples

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Create an infinite array with the scan elevation at 45 degrees. Calculate the scan impedance. By default, the number of summation terms used is 21.

h = infiniteArray('ScanElevation',45);
s = impedance(h,1e9)
s = 84.7925 + 70.6722i

Change the number of summation terms to 51. Calculate the scan impedance again.

numSummationTerms(h,25)
s = impedance(h,1e9)
s = 84.9377 + 70.7043i

Change the number of terms to 101. Increasing the number of summation terms results in a more accurate scan impedance. However, the time required to calculate the scan impedance increases.

numSummationTerms(h,50)
s = impedance(h,1e9)
s = 84.9816 + 70.7090i

## Version History

Introduced in R2015b