Insert algorithm in Lyx 2.1.1 with line numbers

algorithmlatexlyx

I am able to insert algorithms directly with Lyx 2.1.1 using insert->float->algorithm , however the algorithm lines are not numbered in the generated pdf. Is there any option that can number the algorithm lines or any work around to include algorithm in Lyx with line number? I am using the built in IEEE template document in Lyx and assume it should be possible with other templates too.

Best Answer

The default algorithm insertion is just a floating environment. If you want a built-in numbered algorithm, you have to consider adding the algorithm2e module:

enter image description here

Then, also add \LinesNumbered to your Document > Settings... > LaTeX Preamble.

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The above assumes a non-ERT approach to numbered-line algorithms. Of course, if you wish, you can go all out with LaTeX ERT to obtain line numbers in algorithms.

Theoretical background

You need a Bijective Function f. This is necessary so that you can find a inverse function g('abc') = 123 for your f(123) = 'abc' function. This means:

There must be no x1, x2 (with x1 ≠ x2) that will make f(x1) = f(x2),
and for every y you must be able to find an x so that f(x) = y.

How to convert the ID to a shortened URL

Think of an alphabet we want to use. In your case, that's [a-zA-Z0-9]. It contains 62 letters.
Take an auto-generated, unique numerical key (the auto-incremented id of a MySQL table for example).

For this example, I will use 125₁₀ (125 with a base of 10).
Now you have to convert 125₁₀ to X₆₂ (base 62).

125₁₀ = 2×62¹ + 1×62⁰ = [2,1]

This requires the use of integer division and modulo. A pseudo-code example:
```
digits = []

while num > 0
  remainder = modulo(num, 62)
  digits.push(remainder)
  num = divide(num, 62)

digits = digits.reverse
```
Now map the indices 2 and 1 to your alphabet. This is how your mapping (with an array for example) could look like:
```
0  → a
1  → b
...
25 → z
...
52 → 0
61 → 9
```
With 2 → c and 1 → b, you will receive cb₆₂ as the shortened URL.
```
http://shor.ty/cb
```

How to resolve a shortened URL to the initial ID

The reverse is even easier. You just do a reverse lookup in your alphabet.

e9a₆₂ will be resolved to "4th, 61st, and 0th letter in the alphabet".

e9a₆₂ = [4,61,0] = 4×62² + 61×62¹ + 0×62⁰ = 19158₁₀
Now find your database-record with WHERE id = 19158 and do the redirect.