I am working on a Facebook App that needs to be able to average three numbers. But, it always return 0 as the answer. Here is my code:
$y = 100;
$n = 250;
$m = 300;
$number = ($y + $n + $m / 3);
echo 'Index: '.$number;
It always displays Index: 0
Any ideas?
$y = 100;
$n = 250;
$m = 300;
$number = ($y + $n + $m) / 3;
echo 'Index: '.$number;
Also - you missed ; in the end of the first 3 lines
Your parentheses are grouped wrongly. You should be doing:
$number = ($y + $n + $m) / 3;
Two problems:
You are missing ; at the end of these lines:
$y = 100
$n = 250
$m = 300
And to / has higher precedence than + so you need to do:
$number = ($y + $n + $m) / 3;
Related
Does anyone know how to convert a Hex color to HSL in PHP? I've searched but the functions that I’ve found don’t convert precisely the color.
I think the mistake in the second answer is using integer division rather than fmod() when calculating the hue when red is the maximum colour value $hue = (($green - $blue) / $delta) % 6;
I think the mistake in the first answer is in the saturation calculation -
for me $s = $l > 0.5 ? $diff / (2 - $max - $min) : $diff / ($max + $min); is a bit confusing to unpick
Since usually when I want to convert RGB to HSL I want to adjust the lightness value to make a lighter or darker version of the same colour, I have built that into the function below by adding an optional $ladj percent value.
The $hex parameter can be either a hex string (with or without the '#') or an array of RGB values (between 0 and 255)
The return value is an HSL string ready to drop straight in to a CSS colour. ie the values are from 0 to 359 for hue and 0 to 100% for saturation and lightness.
I think this works correctly (based on https://gist.github.com/brandonheyer/5254516)
function hex2hsl($RGB, $ladj = 0) {
//have we got an RGB array or a string of hex RGB values (assume it is valid!)
if (!is_array($RGB)) {
$hexstr = ltrim($RGB, '#');
if (strlen($hexstr) == 3) {
$hexstr = $hexstr[0] . $hexstr[0] . $hexstr[1] . $hexstr[1] . $hexstr[2] . $hexstr[2];
}
$R = hexdec($hexstr[0] . $hexstr[1]);
$G = hexdec($hexstr[2] . $hexstr[3]);
$B = hexdec($hexstr[4] . $hexstr[5]);
$RGB = array($R,$G,$B);
}
// scale the RGB values to 0 to 1 (percentages)
$r = $RGB[0]/255;
$g = $RGB[1]/255;
$b = $RGB[2]/255;
$max = max( $r, $g, $b );
$min = min( $r, $g, $b );
// lightness calculation. 0 to 1 value, scale to 0 to 100% at end
$l = ( $max + $min ) / 2;
// saturation calculation. Also 0 to 1, scale to percent at end.
$d = $max - $min;
if( $d == 0 ){
// achromatic (grey) so hue and saturation both zero
$h = $s = 0;
} else {
$s = $d / ( 1 - abs( (2 * $l) - 1 ) );
// hue (if not grey) This is being calculated directly in degrees (0 to 360)
switch( $max ){
case $r:
$h = 60 * fmod( ( ( $g - $b ) / $d ), 6 );
if ($b > $g) { //will have given a negative value for $h
$h += 360;
}
break;
case $g:
$h = 60 * ( ( $b - $r ) / $d + 2 );
break;
case $b:
$h = 60 * ( ( $r - $g ) / $d + 4 );
break;
} //end switch
} //end else
// make any lightness adjustment required
if ($ladj > 0) {
$l += (1 - $l) * $ladj/100;
} elseif ($ladj < 0) {
$l += $l * $ladj/100;
}
//put the values in an array and scale the saturation and lightness to be percentages
$hsl = array( round( $h), round( $s*100), round( $l*100) );
//we could return that, but lets build a CSS compatible string and return that instead
$hslstr = 'hsl('.$hsl[0].','.$hsl[1].'%,'.$hsl[2].'%)';
return $hslstr;
}
In real life I would break out the hex string to RGB array conversion and the percentage adjustment into separate functions, but have included them here for completeness.
You could also use the percent adjustment to shift the hue or saturation once you've got the colour in HSL format.
function hexToHsl($hex) {
$hex = array($hex[0].$hex[1], $hex[2].$hex[3], $hex[4].$hex[5]);
$rgb = array_map(function($part) {
return hexdec($part) / 255;
}, $hex);
$max = max($rgb);
$min = min($rgb);
$l = ($max + $min) / 2;
if ($max == $min) {
$h = $s = 0;
} else {
$diff = $max - $min;
$s = $l > 0.5 ? $diff / (2 - $max - $min) : $diff / ($max + $min);
switch($max) {
case $rgb[0]:
$h = ($rgb[1] - $rgb[2]) / $diff + ($rgb[1] < $rgb[2] ? 6 : 0);
break;
case $rgb[1]:
$h = ($rgb[2] - $rgb[0]) / $diff + 2;
break;
case $rgb[2]:
$h = ($rgb[0] - $rgb[1]) / $diff + 4;
break;
}
$h /= 6;
}
return array($h, $s, $l);
}
Rewritten (and adjusted a bit) from javascript from https://css-tricks.com/converting-color-spaces-in-javascript/
<?php
function hexToHsl($hex)
{
$red = hexdec(substr($hex, 0, 2)) / 255;
$green = hexdec(substr($hex, 2, 2)) / 255;
$blue = hexdec(substr($hex, 4, 2)) / 255;
$cmin = min($red, $green, $blue);
$cmax = max($red, $green, $blue);
$delta = $cmax - $cmin;
if ($delta === 0) {
$hue = 0;
} elseif ($cmax === $red) {
$hue = (($green - $blue) / $delta) % 6;
} elseif ($cmax === $green) {
$hue = ($blue - $red) / $delta + 2;
} else {
$hue = ($red - $green) / $delta + 4;
}
$hue = round($hue * 60);
if ($hue < 0) {
$hue += 360;
}
$lightness = (($cmax + $cmin) / 2) * 100;
$saturation = $delta === 0 ? 0 : ($delta / (1 - abs(2 * $lightness - 1))) * 100;
if ($saturation < 0) {
$saturation += 100;
}
$lightness = round($lightness);
$saturation = round($saturation);
return "hsl(${hue}, ${saturation}%, ${lightness}%)";
}
Example:
<?php
echo hexToHsl('fbffe0'); // outputs 'hsl(68, 100%, 94%)'
I have a simple equation written in PHP. I have tried to replicate the equation bellow.
When I work out the Equation on pager using the variables I have provided in the PHP I get 2,467.86 (using equation A).
But when I run it in PHP I get 4,2267.11, where have I gone wrong in my PHP ?
Equation A
PHP Equation
<?php
$p = 0;
$i = 0.06;
$c = 12;
$n = 1;
$r = 200;
$x = $i / $c;
$y = pow((1 + $x), ($n * $c));
$vf = $p * $y + (($r * $y - 1) / $x);
?>
<p>Answer:<?php echo $vf; ?></p>
Here:
$vf = $p * $y + ($r * ($y - 1) / $x);
// outputs 2467.1124745799
Your equation was:
$vf = $p * $y + (($r * $y - 1) / $x); // <- NOT $r*$y -1 , but $r*($y-1)
You can see it here - 3v4l
I am building a feedback system: positive, neutral and nagative, I want to get the positive percentage somehow.
$positive = 4;
$neutral = 1;
$negative = 1
So I am trying to get something like 50%. I have tried
$positive / $neutral + $negative;
$positive / $neutral + $negative * 10;
None seem to get the right value.
This should work for you:
<?php
$positive = 4;
$neutral = 1;
$negative = 1;
$total = $positive + $neutral + $negative;
$percentage = ($positive - $negative) / $total * 100;
echo sprintf("%02.2f%%", $percentage);
?>
Output:
50.00%
EDIT:
If you want to count $neutral to positive feedback use this:
$total = $positive + $neutral + $negative;
$percentage = ($positive + $neutral - $negative) / $total * 100;
echo sprintf("%02.2f%%", $percentage);
I am currently trying to make an animated Mandelbrot set visualisation. But right now it won't even render a single frame correctly.
I don't know where I made the mistake. I guess there is an error in the math.Will you please have a look at it?
Here is a how it looks right now:
Here is my mandelbrot function:
function mandelbrot($a, $b, $limit) {
$a_orig = $a;
$b_orig = $b;
$count = 0;
while(($count < $limit) && (sqrt(($a * $a) + ($b * $b)) <= 2)) {
$a = ($a * $a) - ($b * $b) + $a_orig;
$b = (2 * $a * $b) + $b_orig;
$count++;
}
return $count;
}
And here is the entire code:
<?php
function HSVtoRGB(array $hsv) {
list($H,$S,$V) = $hsv;
//1
$H *= 6;
//2
$I = floor($H);
$F = $H - $I;
//3
$M = $V * (1 - $S);
$N = $V * (1 - $S * $F);
$K = $V * (1 - $S * (1 - $F));
//4
switch ($I) {
case 0:
list($R,$G,$B) = array($V,$K,$M);
break;
case 1:
list($R,$G,$B) = array($N,$V,$M);
break;
case 2:
list($R,$G,$B) = array($M,$V,$K);
break;
case 3:
list($R,$G,$B) = array($M,$N,$V);
break;
case 4:
list($R,$G,$B) = array($K,$M,$V);
break;
case 5:
case 6: //for when $H=1 is given
list($R,$G,$B) = array($V,$M,$N);
break;
}
return array($R, $G, $B);
}
function mandelbrot($a, $b, $limit) {
$a_orig = $a;
$b_orig = $b;
$count = 0;
while(($count < $limit) && (sqrt(($a * $a) + ($b * $b)) <= 2)) {
$a = ($a * $a) - ($b * $b) + $a_orig;
$b = (2 * $a * $b) + $b_orig;
$count++;
}
return $count;
}
ini_set("max_execution_time", 0);
header ("Content-Type: image/gif");
$num_frames = 60;
$size = 1024;
$points = array($size);
$image = imagecreate($size, $size);
for($j = 0; $j <= $num_frames; $j++) {
$tmp_color = HSVtoRGB(array(($j + 1) / ($num_frames + 1), 1, 1));
$color[$j] = imagecolorallocate($image, $tmp_color[0] * 255, $tmp_color[1] * 255, $tmp_color[2] * 255);
}
for($x = 0; $x < $size; $x++) {
for($y = 0; $y < $size; $y++) {
imagesetpixel($image, $x, $y, $color[mandelbrot(-2 + ($x * 2.7 / ($size - 1)), -1.35 + ($y * 2.7 / ($size - 1)), $num_frames)]);
}
}
imagegif($image);
imagedestroy($image);
?>
Your complex number square is wrong. You are overwriting the old value of a where it is needed again in the computation of b. So save it in a temporary variable.
Also, the bailout value of 60 iterations is rather small, 200 would be more appropriate for this scale, for more detailed images it should be reasonably rapidly increase.
Use a*a+b*b < 4 instead of the unnecessary square root. One could re-use the values of a*a and b*b which would also solve the problem of the temporary variable.
norm=10
while ... and norm < 4
a2=a*a
b2=b*b
norm=a2+b2
b=2*a*b+b_orig
a=a2-b2+a_orig
end
Hello fellow earthlings. A quesion about RGB color and its usefulness in a simple tiny php code:
Imagine I have variable $colorA containning a valid six char color. say B1B100, a greenish natural color. Now If I would like to make a new color from that, which is, say, ten steps lighter thatn that original color, roughly.
$colorA = B1B100 // original color
php code with little color engine lightening stuff up goes here
$colorB = ?????? // original color lightened up
Is there a php ready function that KNOWS rgb colors something like
php function RGB ( input color, what to do, output color)
Where what to do could be +/- 255 values of brightness etc etc.
Is something like this already possible or am I day dreaming?
rgb-hsl($colorA, +10, $colorB);
If this does not exist, what would be the shortest code for doing this? Suggestions, code or ideas are all answers to me. Thanks.
This SO question has a full-blown PHP script that can convert a RGB to a HSL colour, and increase its H component of a HSL colour - it should be trivial to change to increase L instead.
In general if you want a lighter shade of a particular colour, the most accurate process is to convert from RGB to HSL (or HSV), change the 'L' (or 'V') value which represents lightness, and then convert back to RGB.
This will preserve the "hue", which represents where the colour sits on the spectrum, but change the "tint" (if lightening) or "shade" (if darkening) of that colour.
See http://en.wikipedia.org/wiki/HSL_and_HSV for more information.
On this website: http://www.sitepoint.com/forums/showthread.php?t=586223 they are talking about this code which is originally made by opensource Drupal. Seems to work fine in PHP!?
Now, how do I now indermingle myself with this code and change the lightness of an HSL value, before its outputted as RGB again?
<?php
### RGB >> HSL
function _color_rgb2hsl($rgb) {
$r = $rgb[0]; $g = $rgb[1]; $b = $rgb[2];
$min = min($r, min($g, $b)); $max = max($r, max($g, $b));
$delta = $max - $min; $l = ($min + $max) / 2; $s = 0;
if ($l > 0 && $l < 1) {
$s = $delta / ($l < 0.5 ? (2 * $l) : (2 - 2 * $l));
}
$h = 0;
if ($delta > 0) {
if ($max == $r && $max != $g) $h += ($g - $b) / $delta;
if ($max == $g && $max != $b) $h += (2 + ($b - $r) / $delta);
if ($max == $b && $max != $r) $h += (4 + ($r - $g) / $delta);
$h /= 6;
} return array($h, $s, $l);
}
### HSL >> RGB
function _color_hsl2rgb($hsl) {
$h = $hsl[0]; $s = $hsl[1]; $l = $hsl[2];
$m2 = ($l <= 0.5) ? $l * ($s + 1) : $l + $s - $l*$s;
$m1 = $l * 2 - $m2;
return array(_color_hue2rgb($m1, $m2, $h + 0.33333),
_color_hue2rgb($m1, $m2, $h),
_color_hue2rgb($m1, $m2, $h - 0.33333));
}
### Helper function for _color_hsl2rgb().
function _color_hue2rgb($m1, $m2, $h) {
$h = ($h < 0) ? $h + 1 : (($h > 1) ? $h - 1 : $h);
if ($h * 6 < 1) return $m1 + ($m2 - $m1) * $h * 6;
if ($h * 2 < 1) return $m2;
if ($h * 3 < 2) return $m1 + ($m2 - $m1) * (0.66666 - $h) * 6;
return $m1;
}
### Convert a hex color into an RGB triplet.
function _color_unpack($hex, $normalize = false) {
if (strlen($hex) == 4) {
$hex = $hex[1] . $hex[1] . $hex[2] . $hex[2] . $hex[3] . $hex[3];
} $c = hexdec($hex);
for ($i = 16; $i >= 0; $i -= 8) {
$out[] = (($c >> $i) & 0xFF) / ($normalize ? 255 : 1);
} return $out;
}
### Convert an RGB triplet to a hex color.
function _color_pack($rgb, $normalize = false) {
foreach ($rgb as $k => $v) {
$out |= (($v * ($normalize ? 255 : 1)) << (16 - $k * 8));
}return '#'. str_pad(dechex($out), 6, 0, STR_PAD_LEFT);
}
/* $testrgb = array(0.2,0.75,0.4); //RGB to start with
print_r($testrgb); */
print "Hex: ";
$testhex = "#b7b700";
print $testhex;
$testhex2rgb = _color_unpack($testhex,true);
print "<br />RGB: ";
var_dump($testhex2rgb);
print "<br />HSL color module: ";
$testrgb2hsl = _color_rgb2hsl($testhex2rgb); //Converteren naar HSL
var_dump($testrgb2hsl);
print "<br />RGB: ";
$testhsl2rgb = _color_hsl2rgb($testrgb2hsl); // En weer terug naar RGB
var_dump($testhsl2rgb);
print "<br />Hex: ";
$testrgb2hex = _color_pack($testhsl2rgb,true);
var_dump($testrgb2hex);
?>
PHP does have a couple image manipulation libraries. Either GD or Imagemagick
EDIT: I jumped the gun, these libraries do not have direct PHP color manipulation functions - I honestly assumed they did of a sort after seeing a lot of the things they can do with images via PHP. They do accomplish a lot of cool things. Here's one guy's example.