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0
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1 function yhat=spence15(y)
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2 % function for Spencer's 15-point graduation rule.
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3 % set out following Spencer's hand-calculation method,
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4 % which isn't the shortest computer program!
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5
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6 osev = ones(7,1);
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7 n = length(y);
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8 y = [ osev*y(1); y; osev*y(n) ];
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9
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10 n = length(y);
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11 k = 3:(n-2);
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12 a3 = y(k-1) + y(k) + y(k+1);
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13 a2 = y(k-2) + y(k+2);
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14 y1 = y(k)+3*(a3-a2);
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15
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16 n = length(y1);
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17 k = 1:(n-3);
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18 y2 = y1(k)+y1(k+1)+y1(k+2)+y1(k+3);
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19
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20 n = length(y2);
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21 k = 1:(n-3);
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22 y3 = y2(k)+y2(k+1)+y2(k+2)+y2(k+3);
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23
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24 n = length(y3);
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25 k = 1:(n-4);
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26 y4 = y3(k)+y3(k+1)+y3(k+2)+y3(k+3)+y3(k+4);
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27
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28 yhat = y4/320;
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29 return;
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