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24 lines
777 B
24 lines
777 B
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Exercise 3.77: The integral procedure
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used above was analogous to the “implicit” definition of the infinite stream
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of integers in 3.5.2. Alternatively, we can give a definition of
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integral that is more like integers-starting-from (also in
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3.5.2):
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(define (integral
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integrand initial-value dt)
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(cons-stream
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initial-value
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(if (stream-null? integrand)
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the-empty-stream
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(integral
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(stream-cdr integrand)
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(+ (* dt (stream-car integrand))
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initial-value)
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dt))))
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When used in systems with loops, this procedure has the same problem as does
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our original version of integral. Modify the procedure so that it
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expects the integrand as a delayed argument and hence can be used in the
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solve procedure shown above.
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