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Manual Reference Pages  -  ISED (1)


ised - generating integer and floating point sequences




ised [--m] [--p] [--n] [--f input_file] [--a load_file] [--l apply_to_file] [--x modify_file] [--k awk_file] [--o output_file] [--t code_line] [--d delimiter] [--D int_format] [--F float_format] code ...


ised processes arithmetic expressions involving arrays and returns output array of values. Options and code lines are processed in order of appearance. If ised is called without arguments, it reads from standard input. Press ^D (EOF) or enter a single q to exit when in interactive mode.

When input consists only of arrays of length one (scalars), ised behaves as an ordinary calculator.

Options can also be used from command line in interactive mode or in files, invoked by --f.


--f input_file
  Reads and processes input_file one line at a time, equivalent to giving every line as separate command line argument.

ised --f - is not equivalent to running it without arguments, as the latter also invokes interactive GNU readline prompt.

--a load_file
  Loads load_file into memory. Every line has it’s own memory slot, starting at $1. At the end, line count is saved in memory slot $0. All lines are evaluated before saving.

--l apply_to_file { code | --f file }
  code or file is applied on every line of apply_to_file. Each line is loaded into memory slot $1 while line number is in $0.

--x modify_file { code | --f file }
  Similar to --l, but instead of direct evaluation of lines in modify_file, it splits the line into numbers and strings. The numbers are read and stored into $1, then the code or file is applied. The output has the same form as the input, with the numbers replaced with those returned by the code or file. The $0 memory slot contains the current line number.

--k awk_file { code | --f file }
  Similar to --x, but instead of smartly finding the numbers and storing them all into the same array, it splits each input line at delimiters and stores each column into a separate memory slot, starting with $1. Non-numeric fields are preserved in the output without warning. Changes to the memory slots by the user are reflected in the output. The output is delimited by the delimiter, provided by --d. If code is not terminated by a semicolon, the return value of code or file is appended to the rest of the output.

--o output_file
  Sets the file where standard output is redirected to. Everything after this call will be redirected to output_file, until the next call to --o. Calling --o - reverts back to the standard output.

--t code_line
  code_line is evaluated as usual, but results of every semicolon-terminated substatement are printed as columns. Essentially this is a transposed version of --p option. If code_line contains only one statement, the result is similar to setting delimiter to newline (\n). If code_line is to be appled line-by-line to a file, both --x and --k behave as --l.

--d delimiter
  string delimiter is used to delimit values of output array. Default is space.

--D int_format
  format for printf function for integers. Default: %d.

--F float_format
  format for printf function for floating point values. Default: %g.

--m dump memory page.

--p,--n --p forces ised to print results even when suppressed by semicolon. Every semicolon-terminated substatement is output with terminating newline, so this can be used to split lines when in --l mode. This option persists until it is turned off with --n.

--v show program version and license disclaimer.


ised operators all work on arrays of values. Even single values are treated as arrays with length of one. Spacing between operators and values is optional. Values can be either floating point or integers and retain information about their type unless changed. Same operators behave differently for each type.

In general, operators starting with colon (:) mean component-wise evaluation.

Behaviour in case of illegal arithmetic output (such as division by zero or root of negative values) is uncertain and may return either nan, zero or some other non-standard result. This should not be relied upon as it may change in future releases. The case of integer overflows is to be avoided by user as the program does not issue a warning and the output is wrong and unpredictable. The same holds for conversion of floats to integers. Since version 2.2.3, integer overflows are handled by implicit conversion into floating point type if compiled for x86-64 architecture, but caution is still advised, as the handling may not catch all the problematic cases.


Lines are considered as comments if preceded by #!. If #! appears in the middle of the line, everything behind it is commented out. Completely blank lines are also ignored, but lines with whitespace characters will be treated normally. This way user can seperate several blocks of output by empty lines.

Scripts can be made executable and evaluated without invoking ised explicitly. This is done by including declaration

#!/usr/local/bin/ised --f

in the first line of the script. This line is obviously treated as comment.

In apply-to-file mode, comments and blank lines are preserved in input, but don’t count as active lines and therefore don’t increment line counter. If a file contains mixed data, it can still be processed line-by-line if non-numerical data is commented out.

    Arrays and Separators

Values, separated by commas (,) of spaces ( ) are treated as components of an array. Array separation has lowest precedence, so any operators are evaluated before the array is collected. Nested arrays are flattened before further evaluation. Arrays are enclosed in braces {}, outermost braces are optional.

Output to terminal and history is suppressed by semicolon ; which can occur any number of times in every line (putting it at the end suppreses all output, but still evaluates memory operations, if they’re present).


{1 2 {3 4} 5,6} = {1 2 3 4 5 6}

{1 2+3 4 5*6+7} = {1 5 4 37}

1 5 1+1 = {1 5 2}

    Array Constructors

[n] generates sequence 0..n-1

[n1 n2]
  generates sequence n1..n2 with increment 1. If n2<n1, sequence is descending.

[n1 m1..mi n2]
  generates sequence between n1, n2, but with cycling increments, given as m1..mi.

Example: [0 1 2 10]={0 1 3 4 6 7 9}

(x) repeats number x. This way parentheses can be used for evaluation precedence or for function arguments in scalar context.

(x n) generates array of n repetitions of number x.

(x m1..mi n)
  generates sequence of length n, starting at x with cycling increments m1..mi.

If n is negative, the increments are used |n| times, so for i increments, the output sequence has |n|*i+1 elements.


(0 1 2 10)={0 1 3 4 6 7 9 10 12 13}

(0 [1 5] -1)={0 1 3 6 10 15}

  array grouping

    Component-wise Operators

x:+y x:-y x:*y x:/y x:%y x:^y
  result is an array, where each component is e.g. a sum (or other binary operations above) of corresponding components of x and y. In case of different lengths of arrays, smaller length is used. Operations coresponding to above operators are: addition, substraction, multiplication, division, modulo, exponentiation. Note that modulo works for both integer and non-integer values. Modulo always satisfies this equation: i{x/dy}*y+x%y=x

    Scalar-producing Operators

@+x returns sum of components of x.

@*x returns product of components of x.

x+*y returns a result of alternating addition and subtraction, in the form ((x_0+y_0)*x_1+y_1)*x_2+y_2+...

If x is shorter than y, the elements of x are cyclically reused from the beginning of the array. If y is shorter than x, it is padded with zeroes. This way, a scalar x can be used to evaluate a polynomial with unit leading coefficient.

gcd lcm
  return greatest common divisor and least common multiple of the numbers in the array, respectively. If the array includes noninteger numbers, a warning is issued and an empty array is returned. The result of gcd is negative if an odd number of the array are negative.

avg var

return linear average and variance (mean square dispersion). avg{x} is shorter notation for @+x/d#x and doesn’t require inputting the array twice or storing it in memory.

Example: avg{0 1.5 3}={1.5}

nrm x y
  returns generalized x-norm of vector y. If x is a vector, the result contains all specified norms. x=2 corresponds to Pythagoras’ theorem, which is available also as operator @=.


nrm2{1 1 1}={sqrt3}

nrm{1 3}{1 1}={2. cbrt2}

    Function Maps

sin cos tan atn asn acs abs exp sqt cbt log
  evaluates a function on every element of array, e.g. sin{1 2 3}={sin1 sin2 sin3}. Functions corresponding to above operators are sine, cosine, tangent, arc tangent, arc sine, arc cosine, magnitude, exponential, square root, cubic root, natural logarithm. Long operators atan asin acos sqrt cbrt are also valid. Exponential function is also available as e^, but has a lower precedence (the same as the operator ^). The unary / prefix is also a function map: /x=1.0/x.

x! evaluates factorial on every element of array x. For floating point values it evaluates gamma(x+1). For negative integers, it returns 1.

r f i d prefixes that modify values of array elements.

r rounds values to closest integer.
f returns fractional part of values. It is always in range 0..1 and represents distance to downwards rounded integer, even for negative values.
i returns integer part of values. Expression fx+ix=x always holds.
d converts values to floating point. For example, 1/2=0 but 1/d2=0.5.

ran randomizes elements of array. For integers, it returns random integers strictly smaller than given value. For floating values it returns real numbers.

phi calculates the Euler totient function for positive integers. The nonpositive and noninteger values are skipped.

bj x y by x y

applies x-th Bessel function of first/second kind to array y. x should be one or more integers. Floating point values are cast to integers and a warning is issued.

    Tensor Operators

x+y x-y x*y x/y x%y x^y
  evaluate corresponding operations on every possible pair between elements of x and y. Most useful when one of the arguments is a scalar. Beware, the division operator / acts as an unary operator (inversion) when it has no left operand, or has a space on the left, but not on the right. For instance, /3 is equivalent to 1.0/3.


{1 2 3 4}*{1 -1}={1 -1 2 -2 3 -3 4 -4}

{2 3 -5}*2={4 6 -10}

xey operator for exponential notation. Useful mostly in scalar context, e.g. 1.3e-5, but can be used in general for evaluating exponential notation for all combinations.

xcy evaluates binomial symbol (x over y). It supports floating point values.

Example: 3c{0 1 2 3}={1 3 3 1}

    Polynomial Operators

The following set of operators treat arrays as polynomial coefficients. First element corresponds to zero-order term, and so on, e.g. {1 2 3} <=> 3x^2 + 2x + 1.

x++y x--y
  polynomial addition and substraction. This is similar to operators :+ :-, but the length of output array is equal to length of the larger array.

x**y computes product of two polynomials. It terms of arrays, this evaluates to the convolution of x and y.

x//y x%%y
  computes quotient and remainder in long polynomial division. Returned arrays always contain floating point values, regardless the input. Leading zeroes are trimmed from the output.

px x y
  evaluates polynomial x in points, given in array y.

pd x computes derivative of polynomial x. Equivalent to {x<<-1}:*[1 #x].

pz x returns all real roots of polynomial x. Resulting array is not guaranteed to be sorted in any way.

This operator uses Sturm’s sequence to isolate the roots, and proceeds with Newton-Raphson iteration. It works quite well for well-behaved polynomials. Accuracy is questionable if there are roots with multiplicity 3 or higher.

The algorithms outputs warning messages if the accuracy is questionable, or if the iteration fails to converge to a result.

zp x is the inverse of the pz operator. It takes the set of roots and returns the minimal polynomial with given roots, with the leading coefficient normalized to 1.

pzzp should return the same array as on the input, up to a reordering of elements (excepting the numerical errors in root finding, especially if there are multiple roots). Conversely, zppz does not necessarily return the initial array, as it ignores the normalization factor and irreducible factors that don’t have any real roots.

F x returns the prime factorization of x. If x has many components, the factors are concatenated in a way that makes the product of the output array equal to the product of the input array. That makes the negative integer to produce an additional -1 factor, while floating point input numbers stay intact.

    Vector Operators

x@:y returns dot product of vectors x and y. In case of different array lengths, overhead is discarded.

x@^y returns cross product of vectors x and y, if the vectors are three-dimensional. In general case, it returns components z_i=x_{i+1}*y_{i+2}-x_{i+2}*y_{i+1}.

This generalization is useful for polygon geometry. For polygon with coordinates {x_i,y_i}, the area of the polygon is 0.5*@+{x@^y}. Similar formulas exist for polygon center and other expressions.

@!x normalizes vector x.

@=x returns length of vector x. Shoter notation of general norm: {@=x}={nrm2x}.

    Set Operators

x&y returns elements that are in both x and y.

x|y concatenates arrays x and y. Produces the same result as {x y}.

[deprecated] This operator is an unnecessary waste of notation. It should have had the interleaving effect, now represented by Y.

x\y returns elements of x that are not present in y.

x|&y is the xor operation on arrays. Returns elements, present in only one of the arrays.

xYy interleaves the arrays x and y.

~x reverses order of array x.

Sx sorts array in ascending order.

#x returns number of elements in array.

  counts occurences of elements of x in y. This is selective variant of # operator.

Example: #_{0 1 4}{1 2 3 4 4 1}={0 2 2}

  distributes elements of y into a histogram where elements of x divide the real numbers into bins. The size of the output is one element more than the size of x. The first bin extends from negative infinity to the first element of x and the last extends to the positive infinity. x is expected to be in ascending order.

?x returns indices of nonzero elements of x. Only integer zero counts as zero.

This operator is intended for use with index operator (_), to select elements that satisfy some logical test. For example, x_?{x<1000} returns only elements, smaller than 1000.

To skip an entire array if it doesn’t satisfy a condition, use ? operator in combination with +. For example, x+?{#x==3} prints x only if its length equals 3. This functionality relies on the fact that tensor summation with empty array returns empty array.

?_x y returns the indices of elements of x in the array y. If the element is found more than once, only the first index is returned. If the element is not present in y, a value -1 is returned.

S_x returns the indices that would sort the array x. It’s always true that Sx=x_S_x.

x=y returns 1 if arrays are equal, 0 otherwise.

    Element Selection Operators

x<<y for positive values of y, returns first y values of x (as unix utility head). For negative values, it returns everything except first y values. If y is an array, it concatenates all results. y should be array of integers. Useful for array cycling: {1 2 3 4}<<{-2 2}={3 4 1 2}.

x>>y same as above, except it works from the back of the array.

x_y returns elements of x at indices y. It interpolates for noninteger indices and wraps around for indices out of range.

  conditional selectors. Return elements that satisfy a certain condition.

U unique, deletes duplicate elements
P positive
N negative
O odd
E even
I integers
D floating point values
X prime numbers

min max
  return the smallest and the largest component of the array respectively.

Zx ‘zilch‘ returns an empty array. This operator is useful for suppressing output from functions with side-effects, such as the @ operator.


pi returns 3.14159265358979323846264

deg returns the value of angular degree in radians, 0.017453292519943295769

emc returns Euler-Mascheroni constant, 0.57721566490153286

pm mp plus/minus and minus/plus constants. They output arrays {1,-1} and {-1,1} respectively. They can be used to compute results of multivalued formulas simultaneously, for example quadratic equation.

    Memory Operators

Memory slots are enumerated by integers. For floating point values, integer part is used. This may change in future versions.

Named variables can be used instead of integer enumeration with the use of backticks.

@xy puts array y into memory slots, enumerated by elements of x. x should be integers. Floating point numbers are cast to integers and warning is issued.

$x concatenates arrays found at memory slots, enumerated by x. For negative values, it returns array from history instead of memory, $-1 being most recent entry. x should be integers.

  puts array y into the memory slot, represented by the given <name>.

  retrieves the variable, named by the given <name>.

ised manages memory as hashed map, so a memory position can be every positive integer. Saving array to slot $100 doesn’t allocate any more memory than saving to slot $1. Results are added to history for input lines from files (--f option) or interactive mode, unless the line terminates with a semicolon. Negative slots are reserved for internal use by the named variable system and are not accessible by direct dereference. Instead, history is accessed by the negative arguments of the $ operator.

    Comparison and Equality operators

For logical evaluation, ised provides comparison operators. Result of comparison is 1 for true and 0 for false. Equality and inequality operators also check if types of both values are equal.

For boolean analysis of resulting arrays, use multiplication for and operator and summation for or operator. Incorporating additional operators for this functionality would be redundant, as the result is equivalent. But beware, multiplication and summation have higher precedence than comparison operators, so use grouping operator {} to achieve desirable effect.

x:<y x:>y x:<=y x:>=y x:==y x:<>y
  Comparison and equality, evaluated component-wise. Result is an array with size of the shorter of the input arrays.

x<y x>y x<=y x>=y x==y x<>y
  Same as above, but evaluated on every possible pair of values. Size of the output array is product of input sizes (see Tensor operators for details and example).

    Function definitions

ised implements a rudimentary mechanism for function definitions. It enables storing an expression and evaluate it later upon command. The functions are stored in a map structure and are accessed via integer function ids. A function id is returned when the function is declared. No particular order of the function ids should be assumed. The zero (0) function id is reserved to for an identity function (no-op).

The functions may include memory manipulation, which makes them as versatile as functions in any programming language. They can be designed as procedures ignoring input and output and operate on memory, plain-old-functions that take an argument and return a result, or any combination of both.

  Function declaration. The expression is parsed, stored into the function memory and its unique id is returned. The id is guarranteed to be nonzero. The returned id may be stored in memory and used later. Within the function, operator x is used to refer to the function’s argument. The function is not evaluated at this point.

f::x Function evaluation. f is an array of function ids, which are applied sequentially to the array x, left-to-right. It should be understood as composition of function; the result from the previous function is passed to the next as its argument.

f:::x Function iteration. Array of function ids f is evaluated repeatedly on the argument x. The iteration stops when the argument no longer changes or maximum number of iterations is reached. The maximum number of iterations is 65536 by default, but can be queried and changed using system call Q{105 ...} (see the section on system calls). This operator can be emulated by the ordinary function evaluation and system call for setting the instruction pointer, Q{103 ...}, but the implementation is quite complex. As functional iteration until convergence is common in math, this operator is a valuable shortcut.

f@::x Function map. Array of function ids f is evaluated on each element of the array x. This is meant to allow creation of user functions that don’t have to handle the array nature of the argument themselves.

x This operator evaluates to the argument supplied to the function. In case of nested functions, it refers to the innermost function’s argument. Outside a function, it has the value of the current line (when used with --l or --x), or invalid otherwise.

The function evaluation operator (::) is enough to implement all basic control structures. ised is therefore a Turing complete language.

function call:
conditional execution (if-statement):
  {{false-fun true-fun}_{condition}}::{arg}
switch statement:
  {{fun1 fun2 fun3 fun4 ...}_switch}::{arg}
static repetition (for-statement):
  (fun n)::{arg}
  {@mem {:do-something-with $mem::x :}}::{arg} The implementation of the function must be carefully devised, otherwise the execution might get stuck in an infinite recursion.
general loop (while-statement):
  { body-fun jump-test }::{arg}

Such simple implementation has the loop contents in body-fun and implements jump-fun such that its argument unchanged, but sets the program counter to zero if a condition is met. The program counter is set via system call operator Q{103 n} where n is simply which function in left-hand side of the operator :: is evaluated next. For example, { {:x+1:} {:x Q{103 -{x>10}}:} }::{arg} increments the argument by one until it becomes greater than 10. In that case, the system call sets the program counter to -1, which is out of range and the evaluation stops.

More complex flow control is possible, as the operator Q{103 n} can be used exactly like a goto statement. Q{102} can be used to find the current program counter and calculate relative jumps.

    System calls

The internal state of ised can be accessed and modified using the system call operator Qx. The argument x is an array, where the first component is system call id number and the rest are optional arguments to the system call. The list of system calls will be expanded in future versions of ised.

Example: use ised --l load_file ’$1 Q{$1>3}’ to output the specified file, but terminate as soon as it encounters a number greater than 3.

The system call ids are available as named variables, specified between the backticks as <name>. For instance, a call Q{‘EXIT‘ 42} terminates the program with a return value of 42.

The list of system call numbers and names:
0 [NOP]: no-op
1 [EXIT]: exit
  Exits with return value 0 or the value specified as an optional argument.
100 [BREAK]: break
  Interrupts the loading of files by commands --f, --l, --a or --x and aborts evaluation of the current line.
101 [CONT]: continue
  Aborts evaluation of the current line and proceeds to the next line in the file.
102 [PC]: get program counter
  Returns the index of currently evaluated function in innermost evaluation operator ::.
103 [PCSET]: set program counter
  Sets the index of next evaluated function in innermost operator ::. If argument is out of bounds, it terminates the evaluation. If without arguments, it does nothing.
104 [STACKDEPTH]: get stack depth
  Return the number of nested functions around the call. If not in a function, it returns 0.
105 [MAXITER]: get/set iteration limit
  Without argument, the iteration limit for operator ::: is returned. With argument, it is changed to the given (nonnegative) value.
1000 [HISTORY_COUNT]: get history count
  Returns the number of history entries, or -1 if history is disabled.
1001 [HISTORY_ENABLE]: disable history
  Disables remembering previous results or enables it, if called with a nonzero argument.
1002 [HISTORY_CLEAR]: clear history
  Clears the history.
2000 [MEM_INDEX]: get/set indexing memory slot
  Without arguments, it sets the memory slot where current line number is stored (default is 0). With argument, it sets it.
2001 [MEM_INPUT]: get/set input memory slot
  Same as 2000, but for the memory slot where the current input line is stored (default 1).
2002 [MEM_OFFSET]: get/set file loading offset
  Same as 2000, but for the memory slot where --a continues loading lines to. At startup, this is 0 so the first memory slot filled is $1 and is advanced with each loaded line.
2003 [MEM_CLEAR]: delete from memory
  Clear entire contents of memory if called without arguments. The optional argument is a list of memory slots to delete.
2004 [MEM_LIST]: get memory list
  Lists the occupied memory slots.
2050 [FUN_CLEAR]: delete function
  Clears all the functions if called without arguments. The optional argument is a list of function ids to delete.
2051 [FUN_LIST]: get function list
  Lists the occupied function ids.
3000 [VERSION]: ised version
  Returns the array, containing the version number {major,minor,revision}.
3001 [SIZEOF_INT]: int size
  Returns the size of integer type in bytes.
3002 [SIZEOF_FLOAT]: float size
  Returns the size of float type in bytes.
3003 [DEBUG]: debug level
  Returns the debugging level, set at compile-time.
3004 [READLINE_STATUS]: readline status
  Returns the array indicating if various libreadline functionalities are enabled (use --v for details).
3005 [OVERFLOW_STATUS]: overflow enabled
  Returns 1 if overflow handling was enabled at compile-time and 0 otherwise.
5000 [TIME]: system time
  Returns unix time in seconds if called without arguments. The arguments can be list of values, which specify the time fields to output:
0 [TIME.EPOCH] = epoch
1 [TIME.SEC] = sec
2 [TIME.MIN] = min
3 [TIME.HOUR] = hour
4 [TIME.MONTHDAY] = month-day
5 [TIME.MONTH] = month
6 [TIME.YEAR] = year
7 [TIME.WEEKDAY] = week-day
8 [TIME.YEARDAY] = year-day

For instance, a call Q{‘TIME‘ ‘TIME.YEAR‘ ‘TIME.MONTH‘ ‘TIME.DAY‘} may return the array {2013 10 31}.

5001 [PROCESS_TIME]: process time
  Returns array containing real time, user time and system time in seconds.
5002 [SLEEP]: sleep
  Sleep for the amount of seconds specified in the argument.
5050 [PID]: pid
  Return the PID of this process.


ised ’@0[2 100];$0\{$0*$0}’
  returns all prime numbers up to 100. It utilises memory to prevent code repetition.

ised ’(0 (1 2 10) 10)’
  generates squares of numbers up to 10, by using nested constructors. Inner constructor generates increments for outer constructor.

ised --l file ’$0 ~$1’
  reverses lines of file and prepends line numbers.

ised ’@0 {0.5*{1+sqt5}};r{{$0^[1 20]:-(-$0)^-[1 20]}/sqt5}’
  generates Fibonacci sequence using direct exponential formula.

ised --d ’\n’ ’[0 1/d5 10]’
  generates evenly spaced values between 0 and 10, separated by a newline. Same functionality as

seq 0 0.2 10

ised --d ’\n’ ’[0 pi/100 pi]’ | ised --F ’%+12.6f’ --l - ’d{$1 sin$1 cos$1 tan$1 exp$1 $1^2}’
  generates nicely formatted table of several functions in range between 0 and pi. Note the use of placeholder - for standard input.

ised --o tmp_file --t ’[0 pi/100 pi]’ --o - --F ’%+12.6f’ --l tmp_file ’d{$1 sin$1 cos$1 tan$1 exp$1 $1^2}’
  previous example, achieved in one pass using a temporary intermediate file. Note the use of placeholder - for standard output.

ised ’{1.4^[11]}@:{1./[11]!} exp1.4’
  calculation of exp(1.4) by summation of series, compared to exact value.

ised ’@1 60;@2 72;@3[1 $1];{$1%$3==0}:*{$2%$3==0}:*$3\0’
  returns list of common divisors of 60 and 72. Numbers 60 and 72 are first stored in memory, together with list of possible divisors, for easier readability. Note the use of multiplication for boolean and evaluation. The same can be achieved more elegantly with operator ?:

ised ’@1 60;@2 72;@3[1 $1];$3_?{{$1%$3==0}:*{$2%$3==0}}’

ised ’@1 60;@2 72;{$1*[1 $2]&$2*[1 $1]}_0’
  returns least common multiple of 60 and 72.

ised --d ’+’ ’2^[10]’ | ised
  illustration how changing output format can produce useful input for other programs, in this case, ised itself. This is useful for easier input of operator repetition, for example the power tower:

ised --d ’^’ ’(1/sqt2 10)’ | ised --l - ’-$1’ this outputs solution of equation 2^x=x^2.

ised ’@1{2}@2{3}@3{-5};{-$2+pm*sqt{$2^2-4*$1*$3}}/{2*$1}’
  solves quadratic equation 2x^2+3x-5. Capability of handling arrays is exploited to give both solutions at once. pm operator is shorthand for array {1,-1}.

The same can be achieved with built-in polynomial solver:

ised ’@1{2}@2{3}@3{-5};pz{$3 $2 $1}’

Note that the intermediate variables $1,$2,$3 were only used to make the expression more readable.

yes 0 | ised ’@2{145}’ --l - ’@2{{$2/2 3*$2+1}_{$2%2}} Q{100 $2==1}’
  outputs the Hailstone sequence for the number 145. It uses GNU core utility yes to produce an infinite loop and terminates using a conditional system call 100 (break).

ised --D ’%02d’ --d ’:’ ’Q{5002 60-Q{5000 1}};Q{5000 3 2 1}’
  Waits for the minute to change and then displays the current time, so that the seconds will be zero. It uses the time-related system call utilities 5000 (system time) and 5002 (sleep).


Simon Copar


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