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<?php
/*=======================================================================
// File: JPGRAPH_MESHINTERPOLATE.INC.PHP
// Description: Utility class to do mesh linear interpolation of a matrix
// Created: 2009-03-09
// Ver: $Id: jpgraph_meshinterpolate.inc.php 1709 2009-07-30 08:00:08Z ljp $
//
// Copyright (c) Aditus Consulting. All rights reserved.
//========================================================================
*/
/**
* Utility function to do linear mesh interpolation
* @param $aDat Matrix to interpolate
* @param $aFactor Interpolation factor
*/
function doMeshInterpolate( &$aData, $aFactor ) {
$m = new MeshInterpolate();
$aData = $m->Linear($aData,$aFactor);
}
/**
* Utility class to interpolate a given data matrix
*
*/
class MeshInterpolate {
private $data = array();
/**
* Calculate the mid points of the given rectangle which has its top left
* corner at $row,$col. The $aFactordecides how many spliots should be done.
* i.e. how many more divisions should be done recursively
*
* @param $row Top left corner of square to work with
* @param $col Top left corner of square to work with
* $param $aFactor In how many subsquare should we split this square. A value of 1 indicates that no action
*/
function IntSquare( $aRow, $aCol, $aFactor ) {
if ( $aFactor <= 1 )
return;
$step = pow( 2, $aFactor-1 );
$v0 = $this->data[$aRow][$aCol];
$v1 = $this->data[$aRow][$aCol + $step];
$v2 = $this->data[$aRow + $step][$aCol];
$v3 = $this->data[$aRow + $step][$aCol + $step];
$this->data[$aRow][$aCol + $step / 2] = ( $v0 + $v1 ) / 2;
$this->data[$aRow + $step / 2][$aCol] = ( $v0 + $v2 ) / 2;
$this->data[$aRow + $step][$aCol + $step / 2] = ( $v2 + $v3 ) / 2;
$this->data[$aRow + $step / 2][$aCol + $step] = ( $v1 + $v3 ) / 2;
$this->data[$aRow + $step / 2][$aCol + $step / 2] = ( $v0 + $v1 + $v2 + $v3 ) / 4;
$this->IntSquare( $aRow, $aCol, $aFactor-1 );
$this->IntSquare( $aRow, $aCol + $step / 2, $aFactor-1 );
$this->IntSquare( $aRow + $step / 2, $aCol, $aFactor-1 );
$this->IntSquare( $aRow + $step / 2, $aCol + $step / 2, $aFactor-1 );
}
/**
* Interpolate values in a matrice so that the total number of data points
* in vert and horizontal axis are $aIntNbr more. For example $aIntNbr=2 will
* make the data matrice have tiwce as many vertical and horizontal dta points.
*
* Note: This will blow up the matrcide in memory size in the order of $aInNbr^2
*
* @param $ &$aData The original data matricde
* @param $aInNbr Interpolation factor
* @return the interpolated matrice
*/
function Linear( &$aData, $aIntFactor ) {
$step = pow( 2, $aIntFactor-1 );
$orig_cols = count( $aData[0] );
$orig_rows = count( $aData );
// Number of new columns/rows
// N = (a-1) * 2^(f-1) + 1
$p = pow( 2, $aIntFactor-1 );
$new_cols = $p * ( $orig_cols - 1 ) + 1;
$new_rows = $p * ( $orig_rows - 1 ) + 1;
$this->data = array_fill( 0, $new_rows, array_fill( 0, $new_cols, 0 ) );
// Initialize the new matrix with the values that we know
for ( $i = 0; $i < $new_rows; $i++ ) {
for ( $j = 0; $j < $new_cols; $j++ ) {
$v = 0 ;
if ( ( $i % $step == 0 ) && ( $j % $step == 0 ) ) {
$v = $aData[$i / $step][$j / $step];
}
$this->data[$i][$j] = $v;
}
}
for ( $i = 0; $i < $new_rows-1; $i += $step ) {
for ( $j = 0; $j < $new_cols-1; $j += $step ) {
$this->IntSquare( $i, $j, $aIntFactor );
}
}
return $this->data;
}
}
?>
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