updated because colors were wrong

As GDL starts in DECOMPOSED mode (such does IDL) the colors were wrong.

Author: GillesDuvert

notebooks/demo_gdl.ipynb

@@ -200,9 +200,14 @@
     "x = 2*!PI*0.01*indgen(100)\n",
     "y1 = sin(x)\n",
     "y2 = cos(x)\n",
-    "loadct,39\n",
+    "device,decomposed=0 ;;colors will be numbers from 0 to 255, as index in a colortable\n",
+    "loadct,39 ;; only useful if decomposed=0 : this is the colortable chosen.\n",
+    ";; Note: if, as is the default, decomposed=1, colors are way more numerous (16777216!)\n",
+    ";; but must be defined as 'RRGGBB'x where each color component\n",
+    ";; (Red,Green,Blue) can take the 256 values from '00' to 'FF'\n",
     "window,xsize=800,ysize=500\n",
-    "plot,x,y1,title='Trig Functions',xtitle='Radians',ytitle='Amplitude',xrange=[0,6],charsize=1.5,background=255,color=0\n",
+    "plot,x,y1,title='Trig Functions',xtitle='Radians',ytitle='Amplitude',xrange=[0,6],charsize=1.5,back=255,color=0\n",
+    ";; the equivalent in 'decomposed mode' would have said: background='FFFFFF'x,color='0'x\n",
     "oplot,x,y2,color=50"
    ]
   },
@@ -230,4 +235,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 0
-}
+}