http://mathling.com/core/array  library module

Variable: $RESERVED as 

Function: array
declare function array($rows as xs:integer,
  $columns as xs:integer,
  $data as xs:double*) as map(*)

array()
Construct a new matrix

Params

• rows as xs:integer number of rows in matrix
• columns as xs:integer number of columns in matrix
• data as xs:double* data values (must be $rows X $columns)

Returns

• map(*): matrix

declare function this:array(
  $rows as xs:integer,
  $columns as xs:integer,
  $data as xs:double*
) as map(*)
{
  if ($rows * $columns ne count($data))
  then errors:error("UTIL-BADARRAY", ($rows, $columns, count($data)))
  else (
    map {
      "kind": "array",
      "rows": $rows,
      "columns": $columns,
      "data": $data
    }
  )
}

Errors

UTIL-BADARRAY if number of data values doesn't match size

Function: rows
declare function rows($array as map(*)) as xs:integer

rows()
Accessor for the number of rows in the array

Params

• array as map(*) the array

Returns

• xs:integer: number of rows in array

declare function this:rows($array as map(*)) as xs:integer
{
  $array("rows")
}

Function: columns
declare function columns($array as map(*)) as xs:integer

columns()
Accessor for the number of rows in the array

Params

• array as map(*) the array

Returns

• xs:integer: number of rows in array

declare function this:columns($array as map(*)) as xs:integer
{
  $array("columns")
}

Function: data
declare function data($array as map(*)) as xs:double*

data()
Accessor for the data in the array

Params

• array as map(*) the array

Returns

• xs:double*: sequence of values (row major order)

declare function this:data($array as map(*)) as xs:double*
{
  $array("data")
}

Function: data
declare function data($array as map(*), $data as xs:double*) as map(*)

data()
Settor for the data in the array

Params

• array as map(*) the array
• data as xs:double* the new data

Returns

• map(*): new matrix

declare function this:data($array as map(*), $data as xs:double*) as map(*)
{
  if (this:rows($array) * this:columns($array) ne count($data))
  then errors:error("UTIL-BADARRAY", (this:rows($array), this:columns($array), count($data)))
  else (
    $array=>map:put("data", $data)
  )
}

Errors

UTIL-BADARRAY if number of data values doesn't match size

Function: get
declare function get($array as map(*),
  $row as xs:integer,
  $column as xs:integer) as xs:double

get()
Get a specific data value

Params

• array as map(*): the array
• row as xs:integer: the row number
• column as xs:integer: the column number

Returns

• xs:double: data value array[row, column]

declare function this:get(
  $array as map(*),
  $row as xs:integer,
  $column as xs:integer
) as xs:double
{
  this:data($array)[($row - 1)*$array("columns") + $column]
}

Function: row
declare function row($array as map(*),
  $row as xs:integer) as xs:double*

row()
Return all the values from the given row

Params

• array as map(*): the array
• row as xs:integer: the row number

Returns

• xs:double*: values in row in column order

declare function this:row(
  $array as map(*),
  $row as xs:integer
) as xs:double*
{
  if ($row lt 1 or $row gt $array("rows")) then () else
  let $data := $array("data")
  let $num-columns := $array("columns")
  let $ixs :=
    for $col in 1 to $num-columns
    return ($row - 1)*$num-columns + $col
  for $ix in $ixs
  return $data[$ix]
}

Function: column
declare function column($array as map(*),
  $column as xs:integer) as xs:double*

column()
Return all the values from the given column

Params

• array as map(*): the array
• column as xs:integer: the column number

Returns

• xs:double*: values in column in row order

declare function this:column(
  $array as map(*),
  $column as xs:integer
) as xs:double*
{
  if ($column lt 1 or $column gt $array("columns")) then () else
  let $data := $array("data")
  let $num-rows := $array("rows")
  let $num-columns := $array("columns")
  let $ixs :=
    for $row in 1 to $num-rows
    return ($row - 1)*$num-columns + $column
  for $ix in $ixs
  return $data[$ix]
}

Function: diagonal
declare function diagonal($array as map(*)) as xs:double*

diagonal()
Return all the values from the diagonal
Raises an error if the array is not square

Params

• array as map(*): the array

Returns

• xs:double*: values along main diagonal

declare function this:diagonal($array as map(*)) as xs:double*
{
  let $data := $array("data")
  let $num-rows := $array("rows")
  let $num-columns := $array("columns")
  return (
    if ($num-rows != $num-columns) then (
      errors:error("UTIL-MATRIXNOTSQUARE", ($num-rows,$num-columns))
    ) else (
      let $ixs := for $i in 1 to $num-rows return ($i - 1)*$num-columns + $i
      for $ix in $ixs
      return $data[$ix]
    )
  )
}

Errors

UTIL-MATRIXNOTSQUARE if matrix is not square

Function: trace
declare function trace($array as map(*)) as xs:double

trace()
Compute the trace of the array.
Raises an error if the array is not square

Params

• array as map(*): the array

Returns

• xs:double: trace of the array

declare function this:trace($array as map(*)) as xs:double
{
  sum(this:diagonal($array))
}

Errors

UTIL-MATRIXNOTSQUARE if matrix is not square

Function: determinant
declare function determinant($array as map(*)) as xs:double

determinant()
Compute the determinant of the array.
Raises an error if the array is not square

Params

• array as map(*): the array

Returns

• xs:double: determinant

declare function this:determinant($array as map(*)) as xs:double
{
  let $data := $array("data")
  let $num-rows := $array("rows")
  let $num-columns := $array("columns")
  return (
    if ($num-rows != $num-columns) then (
      errors:error("UTIL-MATRIXNOTSQUARE", ($num-rows,$num-columns))
    ) else (
      switch($num-rows)
      case 1 return $data
      case 2 return $data[1]*$data[4] - $data[2]*$data[3]
      case 3 return (
         $data[1]*$data[5]*$data[9] + $data[2]*$data[6]*$data[7] + $data[3]*$data[4]*$data[8]
        -$data[1]*$data[6]*$data[8] - $data[2]*$data[4]*$data[9] - $data[3]*$data[5]*$data[7]
      )
      default return (
        sum(
          for $i in 1 to $num-columns return (
            math:pow(-1, 1 + $i) *
            this:determinant(
              this:array(
                $num-rows - 1,
                $num-columns - 1,
                for $r in 1 to $num-rows
                for $c in 1 to $num-columns
                where $r != 1 and $c != $i
                return $data[($r - 1)*$num-columns + $c]
              )
            )
          )
        )
      )
    )
  )
}

Errors

UTIL-MATRIXNOTSQUARE if matrix is not square

Function: transpose
declare function transpose($array as map(*)) as map(*)

transpose()
Transpose the array.

Params

• array as map(*): the array

Returns

• map(*): the array, transposed

declare function this:transpose($array as map(*)) as map(*)
{
  let $data := $array("data")
  let $num-rows := $array("rows")
  let $num-columns := $array("columns")
  return (
    this:array(
      $num-columns,
      $num-rows,
      for $c in 1 to $num-columns
      for $r in 1 to $num-rows
      return $data[($r - 1)*$num-columns + $c]
    )
  )
}

Function: cofactor-matrix
declare function cofactor-matrix($array as map(*)) as map(*)

cofactor-matrix()
Compute the cofactor matrix for the array. Raises an error if it is not square.

Params

• array as map(*): the array

Returns

• map(*): matrix of cofactors

declare function this:cofactor-matrix($array as map(*)) as map(*)
{
  let $data := $array("data")
  let $num-rows := $array("rows")
  let $num-columns := $array("columns")
  return (
    if ($num-rows != $num-columns) then (
      errors:error("UTIL-MATRIXNOTSQUARE", ($num-rows,$num-columns))
    ) else if ($num-rows = 1) then (
      errors:error("UTIL-CANNOT", ("cofactor-matrix", $data))
    ) else (
      this:array(
        $num-rows,
        $num-columns,
        for $j in 1 to $num-rows
        for $i in 1 to $num-columns
        return (
          math:pow(-1, $i + $j) *
          this:determinant(
            this:array(
              $num-rows - 1,
              $num-columns - 1,
              for $r in 1 to $num-rows
              for $c in 1 to $num-columns
              where $r != $j and $c != $i
              return $data[($r - 1)*$num-columns + $c]
            )
          )
        )
      )
    )
  )
}

Errors

UTIL-MATRIXNOTSQUARE if matrix is not square

Errors

UTIL-CANNOT if matrix is only 1x1

Function: adjoint
declare function adjoint($array as map(*)) as map(*)

adjoint()
Compute the adjoint of the array. Raises an error if it is not square.

Params

• array as map(*): the array

Returns

• map(*): adjoint matrix

declare function this:adjoint($array as map(*)) as map(*)
{
  let $data := $array("data")
  let $num-rows := $array("rows")
  let $num-columns := $array("columns")
  return (
    if ($num-rows != $num-columns) then (
      errors:error("UTIL-MATRIXNOTSQUARE", ($num-rows,$num-columns))
    ) else (
      this:transpose(this:cofactor-matrix($array))
    )
  )
}

Errors

UTIL-MATRIXNOTSQUARE if matrix is not square

Function: inverse
declare function inverse($array as map(*)) as map(*)

inverse()
Compute the inverse of the array. Raises an error if it is not square.

Params

• array as map(*): the array

Returns

• map(*): array inverse

declare function this:inverse($array as map(*)) as map(*)
{
  let $data := $array("data")
  let $num-rows := $array("rows")
  let $num-columns := $array("columns")
  return (
    if ($num-rows != $num-columns) then (
      errors:error("UTIL-MATRIXNOTSQUARE", ($num-rows,$num-columns))
    ) else (
      let $det := this:determinant($array)
      let $adj := this:adjoint($array)
      return this:map($adj, function ($c as xs:double) as xs:double {$c div $det})
    )
  )
}

Errors

UTIL-MATRIXNOTSQUARE if matrix is not square

Function: times
declare function times($array as map(*), $k as xs:double) as map(*)

times()
Scalar multiplication of an array by a constant.

Params

• array as map(*): the array
• k as xs:double: multiplier

Returns

• map(*): k*array

declare function this:times($array as map(*), $k as xs:double) as map(*)
{
  this:map($array, function ($c as xs:double) { $c*$k })
}

Function: multiply
declare function multiply($a1 as map(*), $a2 as map(*)) as map(*)

multiply()
Matrix multiplication.

Params

• a1 as map(*): one array
• a2 as map(*): another array

Returns

• map(*): a1*a2

declare function this:multiply($a1 as map(*), $a2 as map(*)) as map(*)
{
  if (this:columns($a1) != this:rows($a2)) then (
    errors:error("UTIL-MATRIXNOTCOMPAT", ("multiply", this:rows($a1), this:columns($a1), this:rows($a2), this:columns($a2)))
  ) else (
    let $rows1 := this:rows($a1)
    let $columns1 := this:columns($a1)
    let $data1 := this:data($a1)
    let $rows2 := this:rows($a2)
    let $columns2 := this:columns($a2)
    let $data2 := this:data($a2)
    return (
      this:array($rows1, $columns2, 
        for $r in 1 to $rows1
        for $c in 1 to $columns2
        let $row := this:row($a1, $r)
        let $col := this:column($a2, $c)
        return sum(for $d at $i in $row return $d * $col[$i])
      )
    )
  )
}

Errors

UTIL-MATRIXNOTCOMPAT if the array sizes are incompatible

Function: add
declare function add($a1 as map(*), $a2 as map(*)) as map(*)

add()
Matrix addition

Params

• a1 as map(*): one array
• a2 as map(*): another array

Returns

• map(*): a1+a2

declare function this:add($a1 as map(*), $a2 as map(*)) as map(*)
{
  if (this:columns($a1) != this:columns($a2) or this:rows($a1) != this:rows($a2)) then (
    errors:error("UTIL-MATRIXNOTCOMPAT", ("add", this:rows($a1), this:columns($a1), this:rows($a2), this:columns($a2)))
  ) else (
    let $rows1 := this:rows($a1)
    let $columns1 := this:columns($a1)
    let $data1 := this:data($a1)
    let $rows2 := this:rows($a2)
    let $columns2 := this:columns($a2)
    let $data2 := this:data($a2)
    return (
      this:array($rows1, $columns1, 
        for $d at $i in $data1 return $d + $data2[$i]
      )
    )
  )
}

Errors

UTIL-MATRIXNOTCOMPAT if the array sizes are incompatible

Function: subtract
declare function subtract($a1 as map(*), $a2 as map(*)) as map(*)

subtract()
Matrix subtraction

Params

• a1 as map(*): one array
• a2 as map(*): another array

Returns

• map(*): a1-a2

declare function this:subtract($a1 as map(*), $a2 as map(*)) as map(*)
{
  if (this:columns($a1) != this:columns($a2) or this:rows($a1) != this:rows($a2)) then (
    errors:error("UTIL-MATRIXNOTCOMPAT", ("subtract", this:rows($a1), this:columns($a1), this:rows($a2), this:columns($a2)))
  ) else (
    let $rows1 := this:rows($a1)
    let $columns1 := this:columns($a1)
    let $data1 := this:data($a1)
    let $rows2 := this:rows($a2)
    let $columns2 := this:columns($a2)
    let $data2 := this:data($a2)
    return (
      this:array($rows1, $columns1, 
        for $d at $i in $data1 return $d - $data2[$i]
      )
    )
  )
}

Errors

UTIL-MATRIXNOTCOMPAT if the array sizes are incompatible

Function: map
declare function map($array as map(*), $f as function(xs:double) as xs:double) as map(*)

map()
Run a function over every item in the array, return the new array, preserving properties.

Params

• array as map(*): the array
• f as function(xs:double)asxs:double: function to apply to all the data in the array

Returns

• map(*): new array

declare function this:map($array as map(*), $f as function(xs:double) as xs:double) as map(*)
{
  util:merge-into(
    $array,
    map {"data": for-each(this:data($array), $f)}
  )
}

Function: snap
declare function snap($array as map(*)) as map(*)

snap()
Snap every value in the array to an integer. Returns an array with integer data values.
Preserves properties.

Params

• array as map(*): the array

Returns

• map(*): new array

declare function this:snap($array as map(*)) as map(*)
{
  util:merge-into(
    $array,
    map {
      "data":
        for-each(this:data($array),
          function ($c as xs:double) as xs:integer {
            fn:round($c) cast as xs:integer
          }
        )
    }
  )
}

Function: floor
declare function floor($array as map(*)) as map(*)

floor()
Snap every value in the array to the floor of that value, as an integer.
Returns an array with integer data values. Preserves properties.

Params

• array as map(*): the array

Returns

• map(*): new array

declare function this:floor($array as map(*)) as map(*)
{
  util:merge-into(
    $array,
    map {
      "data": 
        for-each(this:data($array), 
          function($c as xs:double) as xs:integer {
            fn:floor($c) cast as xs:integer
          }
        )
    }
  )
}

Function: decimal
declare function decimal($array as map(*), $digits as xs:integer) as map(*)

decimal()
Truncate the number of digits in every value in the array to the given number of digits,
returning the new array. Preserves properties.

Params

• array as map(*): the array
• digits as xs:integer: number of digits to preserve

Returns

• map(*): new array

declare function this:decimal($array as map(*), $digits as xs:integer) as map(*)
{
  util:merge-into(
    $array,
    map {
      "data":
        for-each(this:data($array),
          function($c as xs:double) as xs:double {
            util:decimal($c, $digits)
          }
        )
    }
  )
}

Function: quote
declare function quote($array as map(*)) as xs:string

quote()
Return a string representation of the array, suitable for debugging.

Params

• array as map(*): the array

Returns

• xs:string: string

declare function this:quote($array as map(*)) as xs:string
{
  string-join((
    "[",
    for $row in 1 to this:rows($array)
    return string-join(this:row($array,$row),","),
    "]"
  ),"
")
}

Function: same
declare function same($this as map(*), $other as map(*)) as xs:boolean

same()
Equality test for two arrays. Arrays are the same if they have the same dimensions and data.
Auxiliary properties do not factor into this test.

Params

• this as map(*): one array
• other as map(*)

Returns

• xs:boolean: true if the arrays have the same data and sizes

declare function this:same($this as map(*), $other as map(*)) as xs:boolean
{
  this:rows($this)=this:rows($other) and
  this:columns($this)=this:columns($other) and
  deep-equal(this:data($this), this:data($other))
}

Function: horizontal-blur
declare function horizontal-blur($source as map(*),
  $radius as xs:integer) as map(*)

horizontal-blur()
Quick horizontal blurring.

Params

• source as map(*) source array
• radius as xs:integer radius of blurring (i.e number of pixels distant)

Returns

• map(*): array with values subject to horizontal blurring

declare function this:horizontal-blur (
  $source as map(*),
  $radius as xs:integer
) as map(*)
{
  let $rows := this:rows($source)
  let $columns := this:columns($source)
  let $data := this:data($source)

  let $dest-data := (
    for $y in 1 to this:rows($source)
    let $total1 :=
      sum(for $kx in -$radius to $radius return $data[($y - 1)*$columns + $kx])

    let $totals :=
      fold-left(2 to $columns, $total1,
        function($totals as xs:double*, $x as xs:integer) {
          $totals,
          $totals[last()]
            - ($data[($y - 1)*$columns + $x - $radius - 1],0)[1]
            + ($data[($y - 1)*$columns + $x + $radius],0)[1]
        }
      )

    return (
      for $x in 1 to $columns return $totals[$x] div ($radius * 2 + 1)
    )
  )

  return this:array($rows, $columns, $dest-data)
}

Function: vertical-blur
declare function vertical-blur($source as map(*),
  $radius as xs:integer) as map(*)

vertical-blur()
Quick horizontal blurring.

Params

• source as map(*) source array
• radius as xs:integer radius of blurring (i.e number of pixels distant)

Returns

• map(*): array with values subject to vertical blurring

declare function this:vertical-blur (
  $source as map(*),
  $radius as xs:integer
) as map(*)
{
  this:horizontal-blur(this:transpose($source), $radius)=>this:transpose()
}

Function: blur
declare function blur($source as map(*),
  $radius as xs:integer) as map(*)

blur()
Quicker approximation of a Gaussian blur.

Params

• source as map(*) source array
• radius as xs:integer radius of blurring (i.e number of pixels distant)

Returns

• map(*): array with values subject to Gaussian blurring

declare function this:blur(
  $source as map(*),
  $radius as xs:integer
) as map(*)
{
  this:horizontal-blur($source,$radius)=>this:vertical-blur($radius)
}