30 lines
849 B
Elixir
30 lines
849 B
Elixir
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defmodule Growth.Calc.BMI do
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@moduledoc """
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Calculate body mass index
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"""
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@inch_to_centimeter 2.54
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@pound_to_kilogram 0.453592
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@doc """
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Calculate the body mass index for a given weight and height.
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Measurements taken in english unit (pounds and inches) are converted to their metric equivalents (kilograms and centimeters).
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"""
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@spec calculate(:english | :metric, number, number) :: number
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def calculate(:english, weight, height) do
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metric_weight = pound_to_kilogram(weight)
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metric_height = inches_to_centimeters(height)
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calculate(:metric, metric_weight, metric_height)
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end
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def calculate(:metric, weight, height) do
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weight / :math.pow(height / 100.0, 2)
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end
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defp inches_to_centimeters(height), do: height * @inch_to_centimeter
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defp pound_to_kilogram(weight), do: weight * @pound_to_kilogram
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end
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