| 1 | ###
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| 2 | Remove terms that involve a given symbol or expression. For example...
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| 3 |
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| 4 | filter(x^2 + x + 1, x) => 1
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| 5 |
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| 6 | filter(x^2 + x + 1, x^2) => x + 1
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| 7 | ###
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| 8 |
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| 9 |
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| 10 |
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| 11 | Eval_filter = ->
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| 12 | p1 = cdr(p1)
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| 13 | push(car(p1))
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| 14 | Eval()
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| 15 | p1 = cdr(p1)
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| 16 | while (iscons(p1))
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| 17 | push(car(p1))
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| 18 | Eval()
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| 19 | filter()
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| 20 | p1 = cdr(p1)
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| 21 |
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| 22 | ###
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| 23 | For example...
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| 24 |
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| 25 | push(F)
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| 26 | push(X)
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| 27 | filter()
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| 28 | F = pop()
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| 29 | ###
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| 30 |
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| 31 | filter = ->
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| 32 | save()
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| 33 | p2 = pop()
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| 34 | p1 = pop()
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| 35 | filter_main()
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| 36 | restore()
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| 37 |
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| 38 | filter_main = ->
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| 39 | if (car(p1) == symbol(ADD))
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| 40 | filter_sum()
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| 41 | else if (istensor(p1))
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| 42 | filter_tensor()
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| 43 | else if (Find(p1, p2))
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| 44 | push_integer(0)
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| 45 | else
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| 46 | push(p1)
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| 47 |
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| 48 | filter_sum = ->
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| 49 | push_integer(0)
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| 50 | p1 = cdr(p1)
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| 51 | while (iscons(p1))
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| 52 | push(car(p1))
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| 53 | push(p2)
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| 54 | filter()
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| 55 | add()
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| 56 | p1 = cdr(p1)
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| 57 |
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| 58 | filter_tensor = ->
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| 59 | i = 0
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| 60 | n = 0
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| 61 | n = p1.tensor.nelem
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| 62 | p3 = alloc_tensor(n)
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| 63 | p3.tensor.ndim = p1.tensor.ndim
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| 64 | for i in [0...p1.tensor.ndim]
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| 65 | p3.tensor.dim[i] = p1.tensor.dim[i]
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| 66 | for i in [0...n]
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| 67 | push(p1.tensor.elem[i])
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| 68 | push(p2)
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| 69 | filter()
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| 70 | p3.tensor.elem[i] = pop()
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| 71 | push(p3)
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