ndarrayops
Common operations for ndarray arrays
npm install ndarrayops
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Version  1.2.1 last updated 3 months ago 
License  MIT 
Keywords  ndarray, math, operations, scientific, linear, algebra 
Repository  git://github.com/mikolalysenko/ndarrayops.git (git) 
Homepage  https://github.com/mikolalysenko/ndarrayops 
Bugs  https://github.com/mikolalysenko/ndarrayops/issues 
Dependencies  cwisecompiler 
Dependents (28) 
gltexture2d, distancetransform, ballmorphology, ndarraytranslate, voxeldemo, burrowswheeler, glmesh, rectmipmap, ndarrayscratch, tilemipmap, ndarrayconvolve, detectpitch, mikolalysenkohoarders, ndarraygaussianfilter, statickdtree, applycolormap, ndarrayimshow, raymarch, orientationscores, ndarraydownsample2x, and 8 more 
ndarrayops
A collection of common mathematical operations for ndarrays. Implemented using cwise
Usage
First, install the library using npm:
npm install ndarrayops
Then you can import the library by doing:
var ops = require("ndarrayops")
Then you can use the functions as in the following example:
//First, import libraries
var ndarray = require("ndarray")
, ops = require("ndarrayops")
//Next, create some arrays
var a = ndarray(new Float32Array(128*128))
, b = ndarray(new Float32Array(128*128))
, c = ndarray(new Float32Array(128*128))
//Initialize b with some random numbers:
ops.random(b)
//Set c to a constant 1
ops.assigns(c, 1.0)
//Add b and c, store result in a:
ops.add(a, b, c)
//Multiply a by 0.5 in place
ops.mulseq(a, 0.5)
//Print some statistics about a:
console.log(
"inf(a) = ", ops.inf(a),
"sup(a) = ", ops.sup(a),
"argmin(a) = ", ops.argmin(a),
"argmax(a) = ", ops.argmax(a),
"norm1(a) = ", ops.norm1(a))
Conventions
This library implements componentwise operations for all of the operators and Math.* functions in JS, along with a few commonly used aggregate operations. Most of the functions in the library work by applying some symmetric binary operator to a pair of arrays. You call them like this:
ops.add(dest, arg1, arg2)
Which translates into code that works (approximately) like this:
for(var i=0; i<dest.shape[0]; ++i) {
dest[i] = arg1[i] + arg2[i]
}
It is up to you to specify where the result gets store. This library does not create new arrays for you to avoid performing expensive intermediate allocations. There are also a few other variations:
ops.addeq(dest, arg1)
Operators with the eq suffix perform an assignment.
for(var i=0; i<dest.shape[0]; ++i) {
dest[i] += arg1[i]
}
ops.adds(dest, arg1, 1.0)
The s suffix denotes scalar/broadcast operations; so the above would translate to:
for(var i=0; i<dest.shape[0]; ++i) {
dest[i] = arg1[i] + 1.0
}
ops.addseq(dest, 1.0)
The seq suffix is basically the combination of the above, and translates to:
for(var i=0; i<dest.shape[0]; ++i) {
dest[i] += 1.0
}
The following operators follow this rule:
 add[,s,eq,seq]  Addition,
+
 sub[,s,eq,seq]  Subtraction,

 mul[,s,eq,seq]  Multiplication,
*
 div[,s,eq,seq]  Division,
/
 mod[,s,eq,seq]  Modulo,
%
 band[,s,eq,seq]  Bitwise And,
&
 bor[,s,eq,seq]  Bitwise Or,
&
 bxor[,s,eq,seq]  Bitwise Xor,
^
 lshift[,s,eq,seq]  Left shift,
<<
 rshift[,s,eq,seq]  Signed right shift,
>>
 rrshift[,s,eq,seq]  Unsigned right shift,
>>>
 lt[,s,eq,seq]  Less than,
<
 gt[,s,eq,seq]  Greater than,
>
 leq[,s,eq,seq]  Less than or equal,
<=
 geq[,s,eq,seq]  Greater than or equal
>=
 eq[,s,eq,seq]  Equals,
===
 neq[,s,eq,seq]  Not equals,
!==
 and[,s,eq,seq]  Boolean And,
&&
 or[,s,eq,seq]  Boolean Or,

 max[,s,eq,seq]  Maximum,
Math.max
 min[,s,eq,seq]  Minimum,
Math.min
Special Cases
There are a few corner cases that follow slightly different rules. These can be grouped using the following general categories:
Assignment
There are two assignment operators:
 assign
 assigns
op.assign(dest, src)
copies one array into another, while op.assigns(dest, val)
broadcasts a scalar to all elements of an array.
Nullary operators
Nullary operators only take on argument for the array they are assigning to, and don't have any variations. Currently there is only one of these:
 random  Sets each element of an array to a random scalar between 0 and 1,
Math.random()
Unary operators
Unary operators have one of two forms, they can be written as either:
op.abs(dest, arg)
Or:
op.abseq(dest)
The former version sets dest = arg, while in the latter the operation is applied in place. ndarrayops exposes the following unary operators:
 not[,eq]  Boolean not,
!
 bnot[,eq]  Bitwise not,
~
 neg[,eq]  Negative,

 recip[,eq]  Reciprocal,
1.0/
 abs[,eq]  Absolute value,
Math.abs
 acos[,eq]  Inverse cosine,
Math.acos
 asin[,eq]  Inverse sine,
Math.asin
 atan[,eq]  Inverse tangent,
Math.atan
 ceil[,eq]  Ceiling,
Math.ceil
 cos[,eq]  Cosine,
Math.cos
 exp[,eq]  Exponent,
Math.exp
 floor[,eq]  Floor,
Math.floor
 log[,eq]  Logarithm,
Math.log
 round[,eq]  Round,
Math.round
 sin[,eq]  Sine,
Math.sin
 sqrt[,eq]  Square root,
Math.sqrt
 tan[,eq]  Tangent,
Math.tan
Nonsymmetric binary operators
There are also a few nonsymmetric binary operators. These operators have an extra suffix op
which flips the order of the arguments. There are only two of these:
 atan2[,s,eq,seq,op,sop,opeq,sopeq]
 pow[,s,eq,seq,op,sop,opeq,sopeq]
Mapreduce (aggregate) operators
Finally, there are aggregate operators that take an array as input and compute some aggregate result or summary. These functions don't have any special suffixes and all of them take a single array as input.
 equals  Check if two ndarrays are equal
 any  Check if any element of the array is truthy
 all  Checks if any element of the array is falsy
 sum  Sums all elements of the array
 prod  Multiplies all elements of the array
 norm2squared  Computes the squared L2 norm
 norm2  Computes the L2 norm
 norminf  Computes the Linfinity norm
 norm1  Computs the L1 norm
 sup  Max element in array
 inf  Min element in array
 argmin  Index of min element
 argmax  Index of max element
Credits
(c) 2013 Mikola Lysenko. MIT License