Riemann sums

Riemann sum type: left right middle trapezoidal lower upper

The underlying JavaScript code

var brd = JXG.JSXGraph.initBoard('box', {axis:true, boundingbox: [-8, 4, 8, -4]});
var s = brd.create('slider',[[1,3],[5,3],[1,10,50]],{name:'n',snapWidth:1});
var a = brd.create('slider',[[1,2],[5,2],[-10,-3,0]],{name:'start'});
var b = brd.create('slider',[[1,1],[5,1],[0,Math.PI,10]],{name:'end'});
var f = function(x){ return Math.sin(x); };
var plot = brd.create('functiongraph',[f,function(){return a.Value();}, function(){return b.Value();}]);

var os = brd.create('riemannsum',[f, 
    function(){ return s.Value();}, function(){ return document.getElementById('sumtype').value;},
    function(){return a.Value();}, 
    function(){return b.Value();}
    ], 
    {fillColor:'#ffff00', fillOpacity:0.3});

brd.create('text',[-6,-3,function(){ return 'Sum='+(JXG.Math.Numerics.riemannsum(f,s.Value(),document.getElementById('sumtype').value,a.Value(),b.Value())).toFixed(4); }]);