add eng notation

Author: PhilippCo

types/Decimal.php

@@ -23,7 +23,8 @@ class Decimal extends AbstractMultiBaseType
         'thousands' => "\xE2\x80\xAF", // narrow no-break space
         'trimzeros' => true,
         'prefix' => '',
-        'postfix' => ''
+        'postfix' => '',
+	    'engineering' => false
     );
 
     /**
@@ -36,6 +37,27 @@ class Decimal extends AbstractMultiBaseType
      */
     public function renderValue($value, \Doku_Renderer $R, $mode)
     {
+
+    if ($this->config['engineering']) {
+        $unitsh = array('', 'k', 'M', 'G', 'T');
+        $unitsl = array('', 'm', 'µ', 'n', 'p', 'f', 'a');
+
+        $exp   = floor(log10($value)/3);
+
+        if ($exp < 0) {
+                $units = $unitsl;
+                $mul   = -1;
+        } else {
+                $units = $unitsh;
+                $mul   = 1; 
+        }
+
+
+        $R->cdata($this->config['prefix'] . $value / 10**($exp*3) . "\xE2\x80\xAF" . $units[$exp*$mul] . $this->config['postfix'] );
+        return true;
+    }
+
+
         if ($this->config['roundto'] == -1) {
             $value = $this->formatWithoutRounding(
                 $value,
@@ -56,7 +78,8 @@ public function renderValue($value, \Doku_Renderer $R, $mode)
             $value = rtrim($value, $this->config['decpoint']);
         }
 
-        $R->cdata($this->config['prefix'] . $value . $this->config['postfix']);
+
+        $R->cdata($this->config['prefix'] . $value . $this->config['postfix'] );
         return true;
     }