Exact constructions of square-root Helmholtz operator symbols: The focusing quadratic profile

2000 ◽  
Vol 41 (7) ◽  
pp. 4881-4938 ◽  
Author(s):  
Louis Fishman ◽  
Maarten V. de Hoop ◽  
Mattheus J. N. van Stralen
Wave Motion ◽  
1997 ◽  
Vol 26 (2) ◽  
pp. 127-161 ◽  
Author(s):  
Louis Fishman ◽  
A.K. Gautesen ◽  
Zhiming Sun

Vestnik MEI ◽  
2018 ◽  
Vol 5 (5) ◽  
pp. 79-88
Author(s):  
Sergey B. Gashkov ◽  
◽  
Aleksandr B. Frolov ◽  
Elizaveta Р. Popova ◽  
◽  
...  

2013 ◽  
Vol 61 (2) ◽  
pp. 371-377
Author(s):  
M. Siwczyński ◽  
A. Drwal ◽  
S. Żaba

Abstract The simple digital filters are not sufficient for digital modeling of systems with distributed parameters. It is necessary to apply more complex digital filters. In this work, a set of filters, called the digital function filters, is proposed. It consists of digital filters, which are obtained from causal and stable filters through some function transformation. In this paper, for several basic functions: exponential, logarithm, square root and the real power of input filter, the recursive algorithms of the digital function filters have been determined The digital function filters of exponential type can be obtained from direct recursive formulas. Whereas, the other function filters, such as the logarithm, the square root and the real power, require using the implicit recursive formulas. Some applications of the digital function filters for the analysis and synthesis of systems with lumped and distributed parameters (a long line, phase shifters, infinite ladder circuits) are given as well.


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