## hpr2554 :: Gnu Awk - Part 11

 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: ex
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
