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29 lines
938 B
Python
29 lines
938 B
Python
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def sum_of_geometric_progression(
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first_term: int, common_ratio: int, num_of_terms: int
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) -> float:
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""""
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Return the sum of n terms in a geometric progression.
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>>> sum_of_geometric_progression(1, 2, 10)
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1023.0
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>>> sum_of_geometric_progression(1, 10, 5)
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11111.0
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>>> sum_of_geometric_progression(0, 2, 10)
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0.0
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>>> sum_of_geometric_progression(1, 0, 10)
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1.0
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>>> sum_of_geometric_progression(1, 2, 0)
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-0.0
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>>> sum_of_geometric_progression(-1, 2, 10)
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-1023.0
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>>> sum_of_geometric_progression(1, -2, 10)
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-341.0
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>>> sum_of_geometric_progression(1, 2, -10)
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-0.9990234375
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"""
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if common_ratio == 1:
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# Formula for sum if common ratio is 1
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return num_of_terms * first_term
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# Formula for finding sum of n terms of a GeometricProgression
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return (first_term / (1 - common_ratio)) * (1 - common_ratio ** num_of_terms)
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