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Spectral Elements<br />

• Motivation: locally linear wave propagation (no singularities)<br />

73<br />

Spectral Elements (2)<br />

Various approaches for numerical solution of PDEs :<br />

• Finite-element methods:<br />

‣ Discrete approximating function is a polynomial of low degree<br />

‣ Well suited to complex geometry and <strong>full</strong> non-linearities<br />

‣ Accuracy limited by low degree of polynomials<br />

• Spectral-type methods:<br />

‣ Discrete approximating function is a polynomial of high degree<br />

‣ Very accurate (“spectral” accuracy) when exact solution is smooth<br />

‣ Currently limited to linear problems (and no singularities)<br />

‣ Difficult to treat complicated boundaries: use domain decomposition<br />

• p-version of FEM:<br />

‣ Shape functions are polynomials of high degree<br />

‣ Bases & quadrature formulas completely different from spectral methods<br />

74<br />

37

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