erfcinv
The inverse complementary error function is defined as
where erf^{-1}(z)
is the inverse error function.
Installation
$ npm install compute-erfcinv
For use in the browser, use browserify.
Usage
var erfcinv = ;
erfcinv( x[, options] )
Evaluates the inverse complementary error function. x
may be either a number
, an array
, a typed array
, or a matrix
. All numeric values must reside on the interval [0,2]
.
var matrix =datamatouti;out = ;// returns ~0.4769out = ;// returns [ +infinity, 0.4769, 0, -0.4769, -infinity ]data = 0 1 2 ;out = ;// returns [ +infinity, 0, -infinity ]data = data ;out = ;// returns Float64Array( [ +infinity, 0, -infinity ] )data = 4 ;for i = 0; i < 4; i++data i = i / 2;mat = ;/*[ 0 0.51 1.5 ]*/out = ;/*[ +infinity 0.4770 -0.477 ]*/
The function accepts the following options
:
- accessor: accessor
function
for accessingarray
values. - dtype: output
typed array
ormatrix
data type. Default:float64
. - copy:
boolean
indicating if thefunction
should return a new data structure. Default:true
. - path: deepget/deepset key path.
- sep: deepget/deepset key path separator. Default:
'.'
.
For non-numeric arrays
, provide an accessor function
for accessing array
values.
var data ='beep' 0'boop' 05'bip' 1'bap' 15'baz' 2;{return d 1 ;}var out =;// returns [ +infinity, 0.4769, 0, -0.4769, -infinity ]
To deepset an object array
, provide a key path and, optionally, a key path separator.
data ='x':9175'x':9125'x':9101'x':91e-5'x':91e-100'x':95e-324;var out = ;/*[{'x':[9,-0.8134198]},{'x':[9,-0.2253121]},{'x':[9,-0.00886250]},{'x':[9,3.12341327]},{'x':[9,15.0655747]},{'x':[9,27.2130740]}]*/var bool = data === out ;// returns true
By default, when provided a typed array
or matrix
, the output data structure is float64
in order to preserve precision. To specify a different data type, set the dtype
option (see matrix
for a list of acceptable data types).
var data out;data = 1e-5 1e-100 5e-324 ;out =;// returns Int32Array( [3,15,27] )// Works for plain arrays, as well...out =;// returns Uint8Array( [3,15,27] )
By default, the function returns a new data structure. To mutate the input data structure (e.g., when input values can be discarded or when optimizing memory usage), set the copy
option to false
.
var databoolmatouti;data =1751251011e-51e-1005e-324;var out =;// returns [ 0.813 0.225 -0.009 3.123 15.066 27.213 ]bool = data === out ;// returns truedata = 4 ;for i = 0; i < 4; i++data i = i / 2;mat = ;/*[ 0 0.51 1.5 ]*/out =;/*[ +infinity 0.4770 -0.477 ]*/bool = mat === out ;// returns true
Notes
-
If an element is not a numeric value, the evaluated inverse complementary error function is
NaN
.var data out;out = ;// returns NaNout = ;// returns NaNout = ;// returns NaNout = ;// returns [ NaN, NaN, NaN ]{return dx;}data ='x':true'x':'x':{}'x':null;out =;// returns [ NaN, NaN, NaN, NaN ]out =;/*[{'x':NaN},{'x':NaN},{'x':NaN,{'x':NaN}]*/ -
Be careful when providing a data structure which contains non-numeric elements and specifying an
integer
output data type, asNaN
values are cast to0
.var out =;// returns Int8Array( [0,0,0] );
Examples
var matrix =erfcinv = ;var datamatouttmpi;// Plain arrays...data = 100 ;for i = 0; i < datalength; i++data i = Math * 2;out = ;// Object arrays (accessors)...{return dx;}for i = 0; i < datalength; i++data i ='x': data i;out =;// Deep set arrays...for i = 0; i < datalength; i++data i ='x': i data i x;out =;// Typed arrays...data = 10 ;for i = 0; i < datalength; i++data i = Math * 2;tmp = ;out = '';for i = 0; i < datalength; i++out += tmp i ;if i < datalength-1out += ',';// Matrices...mat = ;out = ;// Matrices (custom output data type)...out =;
To run the example code from the top-level application directory,
$ node ./examples/index.js
Tests
Unit
Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:
$ make test
All new feature development should have corresponding unit tests to validate correct functionality.
Test Coverage
This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:
$ make test-cov
Istanbul creates a ./reports/coverage
directory. To access an HTML version of the report,
$ make view-cov
License
Copyright
Copyright © 2014-2015. The Compute.io Authors.