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fish-shell/doc_src/math.txt

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Update documentation display code to run roff on the client system instead of pregenerating documentation and compiling it into program binaries darcs-hash:20061117162438-ac50b-5c4c7f0bd8bf53a16e16ecfead9569e642b7160f.gz
2006-11-18 00:24:38 +08:00
\section math math - Perform mathematics calculations
\subsection math-synopsis Synopsis
Simplify styling
2014-08-01 20:25:41 +08:00
\fish{synopsis}
fix `math` regression The previous change to use `argparse` for parity with every other builtin and function introduced a regression. Invocations that start with a negative number can fail because the negative value looks like an invalid flag.
2017-07-15 07:03:31 +08:00
math [-sN | --scale=N] [--] EXPRESSION
Documentation update Rework for Doxygen >1.8. Moved large parts of the documentation to a simplified format, making use of Markdown enhancements and fixing bad long options.
2014-08-01 10:37:32 +08:00
\endfish
Update documentation display code to run roff on the client system instead of pregenerating documentation and compiling it into program binaries darcs-hash:20061117162438-ac50b-5c4c7f0bd8bf53a16e16ecfead9569e642b7160f.gz
2006-11-18 00:24:38 +08:00
\subsection math-description Description
[math] Fix docs We no longer use muparser, but tinyexpr. tinyexpr does not have: - "Statistical functions" like min, max, avg - Multiple expressions separated with "," [ci skip]
2018-02-11 21:00:01 +08:00
`math` is used to perform mathematical calculations. It supports all the usual operations such as addition, subtraction, etc. As well as functions like `abs()`, `sqrt()` and `log2()`. Internally all calculations are performed using floating point representation. Integer values are first converted to floating point before being used. The default output format is integer which causes floating point results to be rounded down to the nearest integer. The `--scale` option can be used to get floating point output.
Revert part of "Revert "Cache math expressions"" 56d91345343a896ccc25d76494975d5c664eca5c contained an LRU cache plus changes to the documentation; 95162ef19d11cee48f952076d1e1ffa5cdb67383 reverted both. This commit re-adds the documentation changes, which are still correct.
2017-09-01 21:55:50 +08:00
Keep in mind that parameter expansion takes before expressions are evaluated. This can be very useful in order to perform calculations involving shell variables or the output of command substitutions, but it also means that parenthesis and the asterisk glob character have to be escaped or quoted.
Make line length, wrapping and spacing consistent
2014-08-19 20:41:23 +08:00
add floating point output to `math` command This makes it easy for the user to request floating point output with the desired number of digits after the decimal point (not to be confused with significant digits). Note that this is just a thin wrapper so someone can say `math -s3 10 / 3` rather than `math "scale=3; 10 /3"`. Resolves #1643
2016-05-03 11:53:48 +08:00
The following options are available:
Change how `math` rounds integer results We need our `math` builtin to behave like `bc` with respect to rounding floating point values to integer to avoid breaking to many existing uses. So when scale is zero round down to the nearest integer. Another change for #3157.
2017-08-24 08:31:04 +08:00
- `-sN` or `--scale=N` sets the scale of the result. `N` must be an integer and defaults to zero. A scale of zero causes results to be rounded down to the nearest integer. So `3/2` returns `1` rather than `2` which `1.5` would normally round to. This is for compatibility with `bc` which was the basis for this command prior to fish 3.0.0. Scale values greater than zero causes the result to be rounded using the usual rules to the specified number of decimal places.
add floating point output to `math` command This makes it easy for the user to request floating point output with the desired number of digits after the decimal point (not to be confused with significant digits). Note that this is just a thin wrapper so someone can say `math -s3 10 / 3` rather than `math "scale=3; 10 /3"`. Resolves #1643
2016-05-03 11:53:48 +08:00
\subsection return-values Return Values
Implement bare minimum builtin `math` command This is the second baby step in resolving #3157. Implement a bare minimum builtin `math` command. This is solely to ensure that fish can be built and run in the Travis build environments. This is okay since anyone running `builtin math` today is already getting an error response. Also, more work is needed to support bare var references, multiple result values, etc.
2017-08-23 10:57:30 +08:00
If the expression is successfully evaluated the return `status` is zero (success) else one.
Extend documentation for the math function darcs-hash:20061212171037-ac50b-1b9d0f51b284925fe0fc3020774ec32bb1414ce7.gz
2006-12-13 01:10:37 +08:00
[math] Document scientific notation
2018-02-27 00:55:17 +08:00
\subsection math-syntax
`math` knows some operators, constants, functions and can (obviously) read numbers.
For numbers, `.` is always the radix character regardless of locale - `2.5`, not `2,5`. Scientific notation (`10e5`) is also available.
\subsection math-operators
`math` knows the following operators:
- `+` for addition and `-` for subtraction.
- `*` for multiplication, `/` for division.
- `^` for exponentiation.
- `%` for modulo.
- `(` and `)` for grouping.
They are all used in an infix manner - `5 + 2`, not `+ 5 2`.
[math] Fix docs We no longer use muparser, but tinyexpr. tinyexpr does not have: - "Statistical functions" like min, max, avg - Multiple expressions separated with "," [ci skip]
2018-02-11 21:00:01 +08:00
\subsection math-constants
`math` knows the following constants:
- `e` - Euler's number.
- `pi` - You know that one. Half of Tau.
Use them without a leading `$`.
\subsection math-functions
`math` supports the following functions:
- `abs`
- `acos`
- `asin`
- `atan`
- `atan2`
- `ceil`
- `cos`
- `cosh`
- `exp` - the base-e exponential function
- `fac` - factorial
- `floor`
- `ln`
- `log` or `log10` - the base-10 logarithm
- `ncr`
- `npr`
- `pow(x,y)` returns x to the y (and can be written as `x ^ y`)
- `sin`
- `sinh`
- `sqrt`
- `tan`
- `tanh`
All of the trigonometric functions use radians.
Help cleanup Large list of changes, including formatting and typos for most commands. More substantive changes have been made to alias, bind, block, break, builtin, case, cd, commandline, count, else, emit, fish_config, funced, function, functions, history, math, mimedb, nextd, not, popd, prevd, pushd, pwd, random, read, set, set_color, switch, test, trap, type, ulimit, umask, and while.
2013-05-12 15:56:01 +08:00
\subsection math-example Examples
Documentation update Rework for Doxygen >1.8. Moved large parts of the documentation to a simplified format, making use of Markdown enhancements and fixing bad long options.
2014-08-01 10:37:32 +08:00
`math 1+1` outputs 2.
Help cleanup Large list of changes, including formatting and typos for most commands. More substantive changes have been made to alias, bind, block, break, builtin, case, cd, commandline, count, else, emit, fish_config, funced, function, functions, history, math, mimedb, nextd, not, popd, prevd, pushd, pwd, random, read, set, set_color, switch, test, trap, type, ulimit, umask, and while.
2013-05-12 15:56:01 +08:00
[math] Fix docs We no longer use muparser, but tinyexpr. tinyexpr does not have: - "Statistical functions" like min, max, avg - Multiple expressions separated with "," [ci skip]
2018-02-11 21:00:01 +08:00
`math $status - 128` outputs the numerical exit status of the last command minus 128.
add floating point output to `math` command This makes it easy for the user to request floating point output with the desired number of digits after the decimal point (not to be confused with significant digits). Note that this is just a thin wrapper so someone can say `math -s3 10 / 3` rather than `math "scale=3; 10 /3"`. Resolves #1643
2016-05-03 11:53:48 +08:00
`math 10 / 6` outputs `1`.
`math -s0 10.0 / 6.0` outputs `1`.
`math -s3 10 / 6` outputs `1.666`.
[math] Fix docs We no longer use muparser, but tinyexpr. tinyexpr does not have: - "Statistical functions" like min, max, avg - Multiple expressions separated with "," [ci skip]
2018-02-11 21:00:01 +08:00
`math "sin(pi)"` outputs `0`.
Revert "Cache math expressions" This reverts commit 56d91345343a896ccc25d76494975d5c664eca5c. An LRU cache in the shell for math seems like overkill.
2017-09-01 15:25:40 +08:00
Revert part of "Revert "Cache math expressions"" 56d91345343a896ccc25d76494975d5c664eca5c contained an LRU cache plus changes to the documentation; 95162ef19d11cee48f952076d1e1ffa5cdb67383 reverted both. This commit re-adds the documentation changes, which are still correct.
2017-09-01 21:55:50 +08:00
\subsection math-notes Compatibility notes
fix `math` regression The previous change to use `argparse` for parity with every other builtin and function introduced a regression. Invocations that start with a negative number can fail because the negative value looks like an invalid flag.
2017-07-15 07:03:31 +08:00
[math] Fix docs We no longer use muparser, but tinyexpr. tinyexpr does not have: - "Statistical functions" like min, max, avg - Multiple expressions separated with "," [ci skip]
2018-02-11 21:00:01 +08:00
Fish 1.x and 2.x releases relied on the `bc` command for handling `math` expressions. Starting with fish 3.0.0 fish uses the tinyexpr library and evaluates the expression without the involvement of any external commands.
Implement bare minimum builtin `math` command This is the second baby step in resolving #3157. Implement a bare minimum builtin `math` command. This is solely to ensure that fish can be built and run in the Travis build environments. This is okay since anyone running `builtin math` today is already getting an error response. Also, more work is needed to support bare var references, multiple result values, etc.
2017-08-23 10:57:30 +08:00
Revert part of "Revert "Cache math expressions"" 56d91345343a896ccc25d76494975d5c664eca5c contained an LRU cache plus changes to the documentation; 95162ef19d11cee48f952076d1e1ffa5cdb67383 reverted both. This commit re-adds the documentation changes, which are still correct.
2017-09-01 21:55:50 +08:00
You don't need to use `--` before the expression even if it begins with a minus sign which might otherwise be interpreted as an invalid option. If you do insert `--` before the expression it will cause option scanning to stop just like for every other command and it won't be part of the expression.
Implement bare minimum builtin `math` command This is the second baby step in resolving #3157. Implement a bare minimum builtin `math` command. This is solely to ensure that fish can be built and run in the Travis build environments. This is okay since anyone running `builtin math` today is already getting an error response. Also, more work is needed to support bare var references, multiple result values, etc.
2017-08-23 10:57:30 +08:00
[docs] Remove mention of cached variables from `math` The variable cache was removed in 95162ef19d11cee48f952076d1e1ffa5cdb67383, so this is now wrong.
2018-02-05 06:24:29 +08:00
Note that the modulo operator (`x % y`) is not well defined for floating point arithmetic. Fish rounds down all floating point values to the nearest integer before performing the modulo operation. So `10.5 % 6.1` is `4`, regardless of what `--scale` value is in effect.
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