HPR2554: Gnu Awk - Part 11

Hacker Public Radio

Awk Part 11

Gnu Awk Documentation: https://www.gnu.org/software/gawk/manual/gawk.html#String-Functions

Numerical functions

• atan2: arctangent of y / x in randians
• cos: cosine of x in radians
• exp: e^x
• int: floor float to int
• log: natrual log
• randn: (pseudo) random number between 0 and 1
• sin: sine of x in radians
• sqrt: square root
• srand: (pseudo) random between 0 and 1, manually setting the seed

String functions

• asort: array sort. Returns array with the values sorted
• asori: array sort. Returns array with the keys (index) sorted
• gensub: Search the target string target for matches of the regular expression regexp. Returns string with substituted text.
• gsub: Search target for all of the longest, leftmost, nonoverlapping matching substrings it can find and replace them with replacement. Returns string with substituted text.
• sub: Search target, which is treated as a string, for the leftmost, longest substring matched by the regular expression regexp. Returns string with substituted text.
• index: Search the string in for the first occurrence of the string find. Returns the position where that occurence begins
• length: returns length of string
• match: Search string for the longest, leftmost substring matched by the regular expression regexp and return the character position (index) at which that substring begins.
• split: Divide string into pieces delimted by field separator. Returns an array of strings
• sprintf: Allows you to store the a string in the that would have been the output of printf into a variable
• strtonum: Turn octal representation to number
• substr: Substring starting at position x for length of y. Returns string
• tolower: Lower-case the string
• toupper: Upper-case the string

References

• Trigonometric functions: https://en.wikipedia.org/wiki/Trigonometric_functions
• Psuedo random number seed: https://en.wikipedia.org/wiki/Random_seed
• Natural log to log 10: https://math.stackexchange.com/questions/107574/from-natural-log-to-log-base-10#107576