1<?php
2/*=======================================================================
3 // File:        JPGRAPH_UTILS.INC
4 // Description: Collection of non-essential "nice to have" utilities
5 // Created:     2005-11-20
6 // Ver:         $Id: jpgraph_utils.inc.php 1777 2009-08-23 17:34:36Z ljp $
7 //
8 // Copyright (c) Asial Corporation. All rights reserved.
9 //========================================================================
10 */
11
12//===================================================
13// CLASS FuncGenerator
14// Description: Utility class to help generate data for function plots.
15// The class supports both parametric and regular functions.
16//===================================================
17class FuncGenerator {
18    private $iFunc='',$iXFunc='',$iMin,$iMax,$iStepSize;
19
20    function __construct($aFunc,$aXFunc='') {
21        $this->iFunc = $aFunc;
22        $this->iXFunc = $aXFunc;
23    }
24
25    function E($aXMin,$aXMax,$aSteps=50) {
26        $this->iMin = $aXMin;
27        $this->iMax = $aXMax;
28        $this->iStepSize = ($aXMax-$aXMin)/$aSteps;
29
30        if( $this->iXFunc != '' )
31        $t = 'for($i='.$aXMin.'; $i<='.$aXMax.'; $i += '.$this->iStepSize.') {$ya[]='.$this->iFunc.';$xa[]='.$this->iXFunc.';}';
32        elseif( $this->iFunc != '' )
33        $t = 'for($x='.$aXMin.'; $x<='.$aXMax.'; $x += '.$this->iStepSize.') {$ya[]='.$this->iFunc.';$xa[]=$x;} $x='.$aXMax.';$ya[]='.$this->iFunc.';$xa[]=$x;';
34        else
35        JpGraphError::RaiseL(24001);//('FuncGenerator : No function specified. ');
36
37        @eval($t);
38
39        // If there is an error in the function specifcation this is the only
40        // way we can discover that.
41        if( empty($xa) || empty($ya) )
42        JpGraphError::RaiseL(24002);//('FuncGenerator : Syntax error in function specification ');
43
44        return array($xa,$ya);
45    }
46}
47
48
49//=============================================================================
50// CLASS DateScaleUtils
51// Description: Help to create a manual date scale
52//=============================================================================
53define('DSUTILS_MONTH',1); // Major and minor ticks on a monthly basis
54define('DSUTILS_MONTH1',1); // Major and minor ticks on a monthly basis
55define('DSUTILS_MONTH2',2); // Major ticks on a bi-monthly basis
56define('DSUTILS_MONTH3',3); // Major icks on a tri-monthly basis
57define('DSUTILS_MONTH6',4); // Major on a six-monthly basis
58define('DSUTILS_WEEK1',5); // Major ticks on a weekly basis
59define('DSUTILS_WEEK2',6); // Major ticks on a bi-weekly basis
60define('DSUTILS_WEEK4',7); // Major ticks on a quod-weekly basis
61define('DSUTILS_DAY1',8); // Major ticks on a daily basis
62define('DSUTILS_DAY2',9); // Major ticks on a bi-daily basis
63define('DSUTILS_DAY4',10); // Major ticks on a qoud-daily basis
64define('DSUTILS_YEAR1',11); // Major ticks on a yearly basis
65define('DSUTILS_YEAR2',12); // Major ticks on a bi-yearly basis
66define('DSUTILS_YEAR5',13); // Major ticks on a five-yearly basis
67
68
69class DateScaleUtils {
70    public static $iMin=0, $iMax=0;
71
72    private static $starthour,$startmonth, $startday, $startyear;
73    private static $endmonth, $endyear, $endday;
74    private static $tickPositions=array(),$minTickPositions=array();
75    private static $iUseWeeks = true;
76
77    static function UseWeekFormat($aFlg) {
78        self::$iUseWeeks = $aFlg;
79    }
80
81    static function doYearly($aType,$aMinor=false) {
82        $i=0; $j=0;
83        $m = self::$startmonth;
84        $y = self::$startyear;
85
86        if( self::$startday == 1 ) {
87            self::$tickPositions[$i++] = mktime(0,0,0,$m,1,$y);
88        }
89        ++$m;
90
91
92        switch( $aType ) {
93            case DSUTILS_YEAR1:
94                for($y=self::$startyear; $y <= self::$endyear; ++$y ) {
95                    if( $aMinor ) {
96                        while( $m <= 12 ) {
97                            if( !($y == self::$endyear && $m > self::$endmonth) ) {
98                                self::$minTickPositions[$j++] = mktime(0,0,0,$m,1,$y);
99                            }
100                            ++$m;
101                        }
102                        $m=1;
103                    }
104                    self::$tickPositions[$i++] = mktime(0,0,0,1,1,$y);
105                }
106                break;
107            case DSUTILS_YEAR2:
108                $y=self::$startyear;
109                while( $y <= self::$endyear ) {
110                    self::$tickPositions[$i++] = mktime(0,0,0,1,1,$y);
111                    for($k=0; $k < 1; ++$k ) {
112                        ++$y;
113                        if( $aMinor ) {
114                            self::$minTickPositions[$j++] = mktime(0,0,0,1,1,$y);
115                        }
116                    }
117                    ++$y;
118                }
119                break;
120            case DSUTILS_YEAR5:
121                $y=self::$startyear;
122                while( $y <= self::$endyear ) {
123                    self::$tickPositions[$i++] = mktime(0,0,0,1,1,$y);
124                    for($k=0; $k < 4; ++$k ) {
125                        ++$y;
126                        if( $aMinor ) {
127                            self::$minTickPositions[$j++] = mktime(0,0,0,1,1,$y);
128                        }
129                    }
130                    ++$y;
131                }
132                break;
133        }
134    }
135
136    static function doDaily($aType,$aMinor=false) {
137        $m = self::$startmonth;
138        $y = self::$startyear;
139        $d = self::$startday;
140        $h = self::$starthour;
141        $i=0;$j=0;
142
143        if( $h == 0 ) {
144            self::$tickPositions[$i++] = mktime(0,0,0,$m,$d,$y);
145        }
146        $t = mktime(0,0,0,$m,$d,$y);
147
148        switch($aType) {
149            case DSUTILS_DAY1:
150                while( $t <= self::$iMax ) {
151                    $t = strtotime('+1 day',$t);
152                    self::$tickPositions[$i++] = $t;
153                    if( $aMinor ) {
154                        self::$minTickPositions[$j++] = strtotime('+12 hours',$t);
155                    }
156                }
157                break;
158            case DSUTILS_DAY2:
159                while( $t <= self::$iMax ) {
160                    $t = strtotime('+1 day',$t);
161                    if( $aMinor ) {
162                        self::$minTickPositions[$j++] = $t;
163                    }
164                    $t = strtotime('+1 day',$t);
165                    self::$tickPositions[$i++] = $t;
166                }
167                break;
168            case DSUTILS_DAY4:
169                while( $t <= self::$iMax ) {
170                    for($k=0; $k < 3; ++$k ) {
171                        $t = strtotime('+1 day',$t);
172                        if( $aMinor ) {
173                            self::$minTickPositions[$j++] = $t;
174                        }
175                    }
176                    $t = strtotime('+1 day',$t);
177                    self::$tickPositions[$i++] = $t;
178                }
179                break;
180        }
181    }
182
183    static function doWeekly($aType,$aMinor=false) {
184        $hpd = 3600*24;
185        $hpw = 3600*24*7;
186        // Find out week number of min date
187        $thursday = self::$iMin + $hpd * (3 - (date('w', self::$iMin) + 6) % 7);
188        $week = 1 + (date('z', $thursday) - (11 - date('w', mktime(0, 0, 0, 1, 1, date('Y', $thursday)))) % 7) / 7;
189        $daynumber = date('w',self::$iMin);
190        if( $daynumber == 0 ) $daynumber = 7;
191        $m = self::$startmonth;
192        $y = self::$startyear;
193        $d = self::$startday;
194        $i=0;$j=0;
195        // The assumption is that the weeks start on Monday. If the first day
196        // is later in the week then the first week tick has to be on the following
197        // week.
198        if( $daynumber == 1 ) {
199            self::$tickPositions[$i++] = mktime(0,0,0,$m,$d,$y);
200            $t = mktime(0,0,0,$m,$d,$y) + $hpw;
201        }
202        else {
203            $t = mktime(0,0,0,$m,$d,$y) + $hpd*(8-$daynumber);
204        }
205
206        switch($aType) {
207            case DSUTILS_WEEK1:
208                $cnt=0;
209                break;
210            case DSUTILS_WEEK2:
211                $cnt=1;
212                break;
213            case DSUTILS_WEEK4:
214                $cnt=3;
215                break;
216        }
217        while( $t <= self::$iMax ) {
218            self::$tickPositions[$i++] = $t;
219            for($k=0; $k < $cnt; ++$k ) {
220                $t += $hpw;
221                if( $aMinor ) {
222                    self::$minTickPositions[$j++] = $t;
223                }
224            }
225            $t += $hpw;
226        }
227    }
228
229    static function doMonthly($aType,$aMinor=false) {
230        $monthcount=0;
231        $m = self::$startmonth;
232        $y = self::$startyear;
233        $i=0; $j=0;
234
235        // Skip the first month label if it is before the startdate
236        if( self::$startday == 1 ) {
237            self::$tickPositions[$i++] = mktime(0,0,0,$m,1,$y);
238            $monthcount=1;
239        }
240        if( $aType == 1 ) {
241            if( self::$startday < 15 ) {
242                self::$minTickPositions[$j++] = mktime(0,0,0,$m,15,$y);
243            }
244        }
245        ++$m;
246
247        // Loop through all the years included in the scale
248        for($y=self::$startyear; $y <= self::$endyear; ++$y ) {
249            // Loop through all the months. There are three cases to consider:
250            // 1. We are in the first year and must start with the startmonth
251            // 2. We are in the end year and we must stop at last month of the scale
252            // 3. A year in between where we run through all the 12 months
253            $stopmonth = $y == self::$endyear ? self::$endmonth : 12;
254            while( $m <= $stopmonth ) {
255                switch( $aType ) {
256                    case DSUTILS_MONTH1:
257                        // Set minor tick at the middle of the month
258                        if( $aMinor ) {
259                            if( $m <= $stopmonth ) {
260                                if( !($y==self::$endyear && $m==$stopmonth && self::$endday < 15) )
261                                self::$minTickPositions[$j++] = mktime(0,0,0,$m,15,$y);
262                            }
263                        }
264                        // Major at month
265                        // Get timestamp of first hour of first day in each month
266                        self::$tickPositions[$i++] = mktime(0,0,0,$m,1,$y);
267
268                        break;
269                    case DSUTILS_MONTH2:
270                        if( $aMinor ) {
271                            // Set minor tick at start of each month
272                            self::$minTickPositions[$j++] = mktime(0,0,0,$m,1,$y);
273                        }
274
275                        // Major at every second month
276                        // Get timestamp of first hour of first day in each month
277                        if( $monthcount % 2 == 0 ) {
278                            self::$tickPositions[$i++] = mktime(0,0,0,$m,1,$y);
279                        }
280                        break;
281                    case DSUTILS_MONTH3:
282                        if( $aMinor ) {
283                            // Set minor tick at start of each month
284                            self::$minTickPositions[$j++] = mktime(0,0,0,$m,1,$y);
285                        }
286                        // Major at every third month
287                        // Get timestamp of first hour of first day in each month
288                        if( $monthcount % 3 == 0 ) {
289                            self::$tickPositions[$i++] = mktime(0,0,0,$m,1,$y);
290                        }
291                        break;
292                    case DSUTILS_MONTH6:
293                        if( $aMinor ) {
294                            // Set minor tick at start of each month
295                            self::$minTickPositions[$j++] = mktime(0,0,0,$m,1,$y);
296                        }
297                        // Major at every third month
298                        // Get timestamp of first hour of first day in each month
299                        if( $monthcount % 6 == 0 ) {
300                            self::$tickPositions[$i++] = mktime(0,0,0,$m,1,$y);
301                        }
302                        break;
303                }
304                ++$m;
305                ++$monthcount;
306            }
307            $m=1;
308        }
309
310        // For the case where all dates are within the same month
311        // we want to make sure we have at least two ticks on the scale
312        // since the scale want work properly otherwise
313        if(self::$startmonth == self::$endmonth && self::$startyear == self::$endyear && $aType==1 ) {
314            self::$tickPositions[$i++] = mktime(0 ,0 ,0, self::$startmonth + 1, 1, self::$startyear);
315        }
316
317        return array(self::$tickPositions,self::$minTickPositions);
318    }
319
320    static function GetTicks($aData,$aType=1,$aMinor=false,$aEndPoints=false) {
321        $n = count($aData);
322        return self::GetTicksFromMinMax($aData[0],$aData[$n-1],$aType,$aMinor,$aEndPoints);
323    }
324
325    static function GetAutoTicks($aMin,$aMax,$aMaxTicks=10,$aMinor=false) {
326        $diff = $aMax - $aMin;
327        $spd = 3600*24;
328        $spw = $spd*7;
329        $spm = $spd*30;
330        $spy = $spd*352;
331
332        if( self::$iUseWeeks )
333        $w = 'W';
334        else
335        $w = 'd M';
336
337        // Decision table for suitable scales
338        // First value: Main decision point
339        // Second value: Array of formatting depending on divisor for wanted max number of ticks. <divisor><formatting><format-string>,..
340        $tt = array(
341            array($spw, array(1,DSUTILS_DAY1,'d M',2,DSUTILS_DAY2,'d M',-1,DSUTILS_DAY4,'d M')),
342            array($spm, array(1,DSUTILS_DAY1,'d M',2,DSUTILS_DAY2,'d M',4,DSUTILS_DAY4,'d M',7,DSUTILS_WEEK1,$w,-1,DSUTILS_WEEK2,$w)),
343            array($spy, array(1,DSUTILS_DAY1,'d M',2,DSUTILS_DAY2,'d M',4,DSUTILS_DAY4,'d M',7,DSUTILS_WEEK1,$w,14,DSUTILS_WEEK2,$w,30,DSUTILS_MONTH1,'M',60,DSUTILS_MONTH2,'M',-1,DSUTILS_MONTH3,'M')),
344            array(-1, array(30,DSUTILS_MONTH1,'M-Y',60,DSUTILS_MONTH2,'M-Y',90,DSUTILS_MONTH3,'M-Y',180,DSUTILS_MONTH6,'M-Y',352,DSUTILS_YEAR1,'Y',704,DSUTILS_YEAR2,'Y',-1,DSUTILS_YEAR5,'Y')));
345
346        $ntt = count($tt);
347        $nd = floor($diff/$spd);
348        for($i=0; $i < $ntt; ++$i ) {
349            if( $diff <= $tt[$i][0] || $i==$ntt-1) {
350                $t = $tt[$i][1];
351                $n = count($t)/3;
352                for( $j=0; $j < $n; ++$j ) {
353                    if( $nd/$t[3*$j] <= $aMaxTicks || $j==$n-1) {
354                        $type = $t[3*$j+1];
355                        $fs = $t[3*$j+2];
356                        list($tickPositions,$minTickPositions) = self::GetTicksFromMinMax($aMin,$aMax,$type,$aMinor);
357                        return array($fs,$tickPositions,$minTickPositions,$type);
358                    }
359                }
360            }
361        }
362    }
363
364    static function GetTicksFromMinMax($aMin,$aMax,$aType,$aMinor=false,$aEndPoints=false) {
365        self::$starthour = date('G',$aMin);
366        self::$startmonth = date('n',$aMin);
367        self::$startday = date('j',$aMin);
368        self::$startyear = date('Y',$aMin);
369        self::$endmonth = date('n',$aMax);
370        self::$endyear = date('Y',$aMax);
371        self::$endday = date('j',$aMax);
372        self::$iMin = $aMin;
373        self::$iMax = $aMax;
374
375        if( $aType <= DSUTILS_MONTH6 ) {
376            self::doMonthly($aType,$aMinor);
377        }
378        elseif( $aType <= DSUTILS_WEEK4 ) {
379            self::doWeekly($aType,$aMinor);
380        }
381        elseif( $aType <= DSUTILS_DAY4 ) {
382            self::doDaily($aType,$aMinor);
383        }
384        elseif( $aType <= DSUTILS_YEAR5 ) {
385            self::doYearly($aType,$aMinor);
386        }
387        else {
388            JpGraphError::RaiseL(24003);
389        }
390        // put a label at the very left data pos
391        if( $aEndPoints ) {
392            $tickPositions[$i++] = $aData[0];
393        }
394
395        // put a label at the very right data pos
396        if( $aEndPoints ) {
397            $tickPositions[$i] = $aData[$n-1];
398        }
399
400        return array(self::$tickPositions,self::$minTickPositions);
401    }
402}
403
404//=============================================================================
405// Class ReadFileData
406//=============================================================================
407Class ReadFileData {
408    //----------------------------------------------------------------------------
409    // Desciption:
410    // Read numeric data from a file.
411    // Each value should be separated by either a new line or by a specified
412    // separator character (default is ',').
413    // Before returning the data each value is converted to a proper float
414    // value. The routine is robust in the sense that non numeric data in the
415    // file will be discarded.
416    //
417    // Returns:
418    // The number of data values read on success, FALSE on failure
419    //----------------------------------------------------------------------------
420    static function FromCSV($aFile,&$aData,$aSepChar=',',$aMaxLineLength=1024) {
421        $rh = @fopen($aFile,'r');
422        if( $rh === false ) {
423                return false;
424        }
425        $tmp = array();
426        $lineofdata = fgetcsv($rh, 1000, ',');
427        while ( $lineofdata !== FALSE) {
428            $tmp = array_merge($tmp,$lineofdata);
429            $lineofdata = fgetcsv($rh, $aMaxLineLength, $aSepChar);
430        }
431        fclose($rh);
432
433        // Now make sure that all data is numeric. By default
434        // all data is read as strings
435        $n = count($tmp);
436        $aData = array();
437        $cnt=0;
438        for($i=0; $i < $n; ++$i) {
439            if( $tmp[$i] !== "" ) {
440                $aData[$cnt++] = floatval($tmp[$i]);
441            }
442        }
443        return $cnt;
444    }
445
446    //----------------------------------------------------------------------------
447    // Desciption:
448    // Read numeric data from a file.
449    // Each value should be separated by either a new line or by a specified
450    // separator character (default is ',').
451    // Before returning the data each value is converted to a proper float
452    // value. The routine is robust in the sense that non numeric data in the
453    // file will be discarded.
454    //
455    // Options:
456    // 'separator'     => ',',
457    // 'enclosure'     => '"',
458    // 'readlength'    => 1024,
459    // 'ignore_first'  => false,
460    // 'first_as_key'  => false
461    // 'escape'        => '\',   # PHP >= 5.3 only
462    //
463    // Returns:
464    // The number of lines read on success, FALSE on failure
465    //----------------------------------------------------------------------------
466    static function FromCSV2($aFile, &$aData, $aOptions = array()) {
467        $aDefaults = array(
468            'separator'     => ',',
469            'enclosure'     => chr(34),
470            'escape'        => chr(92),
471            'readlength'    => 1024,
472            'ignore_first'  => false,
473            'first_as_key'  => false
474            );
475
476        $aOptions = array_merge(
477            $aDefaults, is_array($aOptions) ? $aOptions : array());
478
479        if( $aOptions['first_as_key'] ) {
480            $aOptions['ignore_first'] =  true;
481        }
482
483        $rh = @fopen($aFile, 'r');
484
485        if( $rh === false ) {
486            return false;
487        }
488
489        $aData  = array();
490        $aLine  = fgetcsv($rh,
491                          $aOptions['readlength'],
492                          $aOptions['separator'],
493                          $aOptions['enclosure']
494                          /*, $aOptions['escape']     # PHP >= 5.3 only */
495                          );
496
497        // Use numeric array keys for the columns by default
498        // If specified use first lines values as assoc keys instead
499        $keys = array_keys($aLine);
500        if( $aOptions['first_as_key'] ) {
501            $keys = array_values($aLine);
502        }
503
504        $num_lines = 0;
505        $num_cols  = count($aLine);
506
507        while ($aLine !== false) {
508            if( is_array($aLine) && count($aLine) != $num_cols ) {
509                JpGraphError::RaiseL(24004);
510                // 'ReadCSV2: Column count mismatch in %s line %d'
511            }
512
513            // fgetcsv returns NULL for empty lines
514            if( !is_null($aLine) ) {
515                $num_lines++;
516
517                if( !($aOptions['ignore_first'] && $num_lines == 1) && is_numeric($aLine[0]) ) {
518                    for( $i = 0; $i < $num_cols; $i++ ) {
519                        $aData[ $keys[$i] ][] = floatval($aLine[$i]);
520                    }
521                }
522            }
523
524            $aLine = fgetcsv($rh,
525                             $aOptions['readlength'],
526                             $aOptions['separator'],
527                             $aOptions['enclosure']
528                             /*, $aOptions['escape']     # PHP >= 5.3 only*/
529                );
530        }
531
532        fclose($rh);
533
534        if( $aOptions['ignore_first'] ) {
535            $num_lines--;
536        }
537
538        return $num_lines;
539    }
540
541    // Read data from two columns in a plain text file
542    static function From2Col($aFile, $aCol1, $aCol2, $aSepChar=' ') {
543        $lines = @file($aFile,FILE_IGNORE_NEW_LINES|FILE_SKIP_EMPTY_LINES);
544        if( $lines === false ) {
545                return false;
546        }
547        $s = '/[\s]+/';
548        if( $aSepChar == ',' ) {
549                        $s = '/[\s]*,[\s]*/';
550        }
551        elseif( $aSepChar == ';' ) {
552                        $s = '/[\s]*;[\s]*/';
553        }
554        foreach( $lines as $line => $datarow ) {
555                $split = preg_split($s,$datarow);
556                $aCol1[] = floatval(trim($split[0]));
557                $aCol2[] = floatval(trim($split[1]));
558        }
559
560        return count($lines);
561    }
562
563    // Read data from one columns in a plain text file
564    static function From1Col($aFile, $aCol1) {
565        $lines = @file($aFile,FILE_IGNORE_NEW_LINES|FILE_SKIP_EMPTY_LINES);
566        if( $lines === false ) {
567                return false;
568        }
569        foreach( $lines as $line => $datarow ) {
570                $aCol1[] = floatval(trim($datarow));
571        }
572
573        return count($lines);
574    }
575
576    static function FromMatrix($aFile,$aSepChar=' ') {
577        $lines = @file($aFile,FILE_IGNORE_NEW_LINES|FILE_SKIP_EMPTY_LINES);
578        if( $lines === false ) {
579                return false;
580        }
581        $mat = array();
582        $reg = '/'.$aSepChar.'/';
583        foreach( $lines as $line => $datarow ) {
584                $row = preg_split($reg,trim($datarow));
585                foreach ($row as $key => $cell ) {
586                        $row[$key] = floatval(trim($cell));
587                }
588                $mat[] = $row;
589        }
590        return $mat;
591    }
592
593
594}
595
596define('__LR_EPSILON', 1.0e-8);
597//=============================================================================
598// Class LinearRegression
599//=============================================================================
600class LinearRegression {
601        private $ix=array(),$iy=array();
602        private $ib=0, $ia=0;
603        private $icalculated=false;
604        public $iDet=0, $iCorr=0, $iStdErr=0;
605
606        public function __construct($aDataX,$aDataY) {
607                if( count($aDataX) !== count($aDataY) ) {
608                        JpGraph::Raise('LinearRegression: X and Y data array must be of equal length.');
609                }
610                $this->ix = $aDataX;
611                $this->iy = $aDataY;
612        }
613
614        public function Calc() {
615
616                $this->icalculated = true;
617
618                $n = count($this->ix);
619                $sx2 = 0 ;
620                $sy2 = 0 ;
621                $sxy = 0 ;
622                $sx = 0 ;
623                $sy = 0 ;
624
625                for( $i=0; $i < $n; ++$i ) {
626                        $sx2 += $this->ix[$i] * $this->ix[$i];
627                        $sy2 += $this->iy[$i] * $this->iy[$i];
628                        $sxy += $this->ix[$i] * $this->iy[$i];
629                        $sx += $this->ix[$i];
630                        $sy += $this->iy[$i];
631                }
632
633                if( $n*$sx2 - $sx*$sx > __LR_EPSILON ) {
634                        $this->ib = ($n*$sxy - $sx*$sy) / ( $n*$sx2 - $sx*$sx );
635                        $this->ia = ( $sy - $this->ib*$sx ) / $n;
636
637                        $sx = $this->ib * ( $sxy - $sx*$sy/$n );
638                        $sy2 = $sy2 - $sy*$sy/$n;
639                        $sy = $sy2 - $sx;
640
641                        $this->iDet = $sx / $sy2;
642                        $this->iCorr = sqrt($this->iDet);
643                        if( $n > 2 ) {
644                                $this->iStdErr = sqrt( $sy / ($n-2) );
645                        }
646                        else {
647                                $this->iStdErr = NAN ;
648                        }
649                }
650                else {
651                        $this->ib = 0;
652                        $this->ia = 0;
653                }
654
655        }
656
657        public function GetAB() {
658                if( $this->icalculated == false )
659                        $this->Calc();
660                return array($this->ia, $this->ib);
661        }
662
663        public function GetStat() {
664                if( $this->icalculated == false )
665                        $this->Calc();
666                return array($this->iStdErr, $this->iCorr, $this->iDet);
667        }
668
669        public function GetY($aMinX, $aMaxX, $aStep=1) {
670                if( $this->icalculated == false )
671                        $this->Calc();
672
673                $yy = array();
674                $i = 0;
675                for( $x=$aMinX; $x <= $aMaxX; $x += $aStep ) {
676                        $xx[$i  ] = $x;
677                        $yy[$i++] = $this->ia + $this->ib * $x;
678                }
679
680                return array($xx,$yy);
681        }
682
683}
684
685?>
686