Return an array containing the values associated with the given keys. Also see Hash.select.
h = { "cat" => "feline", "dog" => "canine", "cow" => "bovine" } h.values_at("cow", "cat") #=> ["bovine", "feline"]
Yields each environment variable name and value.
If no block is given an Enumerator is returned.
Returns an array containing the environment variable values associated with the given names. See also ENV.select.
Returns the external encoding for files read from ARGF as an Encoding object. The external encoding is the encoding of the text as stored in a file. Contrast with ARGF.internal_encoding, which is the encoding used to represent this text within Ruby.
To set the external encoding use ARGF.set_encoding.
For example:
ARGF.external_encoding #=> #<Encoding:UTF-8>
Returns the internal encoding for strings read from ARGF as an Encoding object.
If ARGF.set_encoding has been called with two encoding names, the second is returned. Otherwise, if Encoding.default_external has been set, that value is returned. Failing that, if a default external encoding was specified on the command-line, that value is used. If the encoding is unknown, nil is returned.
This method is a shortcut for converting a single row (Array) into a CSV String.
The options parameter can be anything CSV::new() understands. This method understands an additional :encoding parameter to set the base Encoding for the output. This method will try to guess your Encoding from the first non-nil field in row, if possible, but you may need to use this parameter as a backup plan.
The :row_sep option defaults to $INPUT_RECORD_SEPARATOR ($/) when calling this method.
This method is a shortcut for converting a single line of a CSV String into an Array. Note that if line contains multiple rows, anything beyond the first row is ignored.
The options parameter can be anything CSV::new() understands.
Returns true if illegal input is handled. See CSV::new for details.
Return the appropriate error message in POSIX-defined format. If no error has occurred, returns nil.
Returns a string for DNS reverse lookup compatible with RFC3172.
Returns the Ruby source filename and line number of the binding object.
Returns the Laplace expansion along given row or column.
Matrix[[7,6], [3,9]].laplace_expansion(column: 1) => 45 Matrix[[Vector[1, 0], Vector[0, 1]], [2, 3]].laplace_expansion(row: 0) => Vector[3, -2]
Hadamard product
Matrix[[1,2], [3,4]].hadamard_product(Matrix[[1,2], [3,2]])
=> 1 4
9 8
Private. Use Matrix#determinant
Returns the determinant of the matrix, using Bareiss’ multistep integer-preserving gaussian elimination. It has the same computational cost order O(n^3) as standard Gaussian elimination. Intermediate results are fraction free and of lower complexity. A matrix of Integers will have thus intermediate results that are also Integers, with smaller bignums (if any), while a matrix of Float will usually have intermediate results with better precision.
Explicit conversion to a Matrix. Returns self