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annotate four.m @ 1253:89dad61cad22 feature/poroelastic

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Make Elastic2dVariable faster and more memory efficient
author Martin Almquist <malmquist@stanford.edu>
date Tue, 04 Feb 2020 10:15:42 -0800
parents f6ada1719420
children
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598
f6ada1719420 Add functions for calculating fourier transforms
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1 % four returns the fourier transform u_hat of the function u and the frequencies w
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2 function [w, u_hat] = four(x, u)
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3 u_hat = fft(u);
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4
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5 N = length(x);
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6 L = x(end) - x(1);
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7
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8 k = shift_k(0:N-1);
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9
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10 u_hat = fftshift(u_hat);
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11
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12 dw = 2*pi/L;
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13 w = dw*k;
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14 end
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15
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16 function k_shifted = shift_k(k)
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17 N = length(k);
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18 k_shifted = [-floor(N/2):-1, 0, 1:ceil(N/2)-1];
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19 end