nl_tokens: integral ( c^x x ) = c^x / log ( c )
pl_tokens: function ( expr , <mask> ) { if ( expr . type === 'OperatorNode' && expr . op === '^' ) { if ( context . isConstant ( expr . args [ 0 ] ) && expr . args [ 1 ] . equals ( context . variable ) ) { return new OperatorNode ( '/' , 'divide' , [ expr , new FunctionNode ( 'log' , [ expr . args [ 0 ] ] ) ] ) ; } } }