function(expr, context) {
      if(expr.type === "SymbolNode" && expr.name === context.variable.name) {
        return new OperatorNode('*', 'multiply', [
          new OperatorNode('/', 'divide', [
            new ConstantNode(1),
            new ConstantNode(2)
          ]),
          new OperatorNode('^', 'pow', [
            expr.clone(),
            new ConstantNode(2)
          ])
        ]);
      }
    }
function(expr, context) {
      if(expr.type === "SymbolNode" && expr.name === context.variable.name) {
        return new OperatorNode('*', 'multiply', [
          new OperatorNode('/', 'divide', [
            new ConstantNode(1),
            new ConstantNode(2)
          ]),
          new OperatorNode('^', 'pow', [
            expr.clone(),
            new ConstantNode(2)
          ])
        ]);
      }
    }
function ( expr , context ) { if ( expr . type === "SymbolNode" && expr . name === context . variable . name ) { return new OperatorNode ( '*' , 'multiply' , [ new OperatorNode ( '/' , 'divide' , [ new ConstantNode ( 1 ) , new ConstantNode ( 2 ) ] ) , new OperatorNode ( '^' , 'pow' , [ expr . clone ( ) , new ConstantNode ( 2 ) ] ) ] ) ; } }
integral(x, x) = 1/2*x^2
integral ( x x ) = 1 / 2 * x^2