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cs326:daily3

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CSci 326: Daily 3

In iex, run a set of pattern matches. After each match, query the variables involved to see their new bindings. Run these in emacs so you can turn in a transcript file. The patterns:

  • a = 1
  • {c, d} = {2, 3}
  • {x, :abc} = {123, :abc}
  • {x, y} = {333, :abc, “cat”}
  • {x, y, z} = { {:abc, 123}, 42, {:abc, 123} }
  • {x, y, x} = { {:abc, 123}, 42, {:abc, 123} }
  • {x, y, x} = { {:abc, 123}, 42, true }
  • “Elixir ” <> rest = “Elixir Rocks!”
  • [e, f, g] = [4, :five, [6, 7]]
  • [head | tail] = [4, :five, [6, 7]]
  • [head | tail] = “cat”
  • [a, b, c | tail] = [1, 2, 3, 4, 5, 6]

You saw the tuple data type in Daily 1. There are two built-in functions for accessing tuple elements and creating new tuples from existing ones:

  • elem(tp, index) returns the nth value in the tuple tp, starting at 0
  • put_elem(tp, n, value) returns a new tuple replacing the nth element of tp with value

We can represent a quadratic equation as a tuple where each element is a coefficient; for example we can use {:quad, 1, 3, 2} to represent x2 + 3x + 2. Likewise, we can use a tuple to represent a cubic equation, like {:cubic, 1, 3, 2, 16} for x3 + 3x2 + 2x + 16.

  1. Write a function eval_equation that takes a tuple and a value for x and returns the result of evaluating the equation at that value. Use pattern matching and multiple clauses to determine which type of equation you have, quadratic or cubic (assume the tuples are the correct length and contains numbers).
  2. Define your functions in a module Daily3. Name the file containing the module daily3.exs along with code to exercise the function and print the results.
cs326/daily3.1517201786.txt.gz · Last modified: 2018/01/28 22:56 by scarl