1 | ###
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2 | Return the leading coefficient of a polynomial.
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3 |
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4 | Example
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5 |
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6 | leading(5x^2+x+1,x)
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7 |
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8 | Result
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9 |
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10 | 5
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11 |
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12 | The result is undefined if P is not a polynomial.
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13 | ###
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14 |
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15 | Eval_leading = ->
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16 | push(cadr(p1))
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17 | Eval()
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18 | push(caddr(p1))
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19 | Eval()
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20 | p1 = pop()
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21 | if (p1 == symbol(NIL))
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22 | guess()
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23 | else
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24 | push(p1)
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25 | leading()
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26 |
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27 | #define P p1
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28 | #define X p2
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29 | #define N p3
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30 |
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31 | leading = ->
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32 | save()
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33 |
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34 | p2 = pop()
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35 | p1 = pop()
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36 |
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37 | push(p1) # N = degree of P
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38 | push(p2)
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39 | degree()
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40 | p3 = pop()
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41 |
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42 | push(p1) # divide through by X ^ N
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43 | push(p2)
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44 | push(p3)
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45 | power()
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46 | divide()
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47 |
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48 | push(p2) # remove terms that depend on X
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49 | filter()
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50 |
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51 | restore()
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