nl_tokens: integral ( log ( x ) x ) = x * log ( x ) - x
pl_tokens: function ( expr , context , subIntegral ) { if ( expr . type === 'FunctionNode' && expr . name === 'log' && expr . args . length === 1 ) { if ( expr . args . length === 1 && expr . args [ 0 ] . equals ( context . variable ) ) { return new OperatorNode ( '-' , 'subtract' , [ new OperatorNode ( '*' , 'multiply' , [ context . variable , new FunctionNode ( 'log' , [ <mask> . variable ] ) ] ) , context . variable ] ) ; } } }