static double inv_interpolate ( Data [ ] d , int n , double y ) {
  double x = 0 ;
  int i , j ;
  for ( i = 0 ;
  i < n ;
  i ++ ) {
    double xi = d [ i ] . x ;
    for ( j = 0 ;
    j < n ;
    j ++ ) {
      if ( j != i ) {
        xi = xi * ( y - d [ j ] . y ) / ( d [ i ] . y - d [ j ] . y ) ;
      }
    }
    x += xi ;
  }
  return x ;
}

static double inv_interpolate ( Data [ ] d , int n , double y ) { double x = 0 ; int i , j ; for ( i = 0 ; i < n ; i ++ ) { double xi = d [ i ] . x ; for ( j = 0 ; j < n ; j ++ ) { if ( j != i ) { xi = xi * ( y - d [ j ] . y ) / ( d [ i ] . y - d [ j ] . y ) ; } } x += xi ; } return x ; }
(method_declaration (modifiers) type: (floating_point_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier)) (formal_parameter type: (integral_type) name: (identifier)) (formal_parameter type: (floating_point_type) name: (identifier))) body: (block (local_variable_declaration type: (floating_point_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier)) declarator: (variable_declarator name: (identifier))) (for_statement init: (assignment_expression left: (identifier) right: (decimal_integer_literal)) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (floating_point_type) declarator: (variable_declarator name: (identifier) value: (field_access object: (array_access array: (identifier) index: (identifier)) field: (identifier)))) (for_statement init: (assignment_expression left: (identifier) right: (decimal_integer_literal)) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (binary_expression left: (binary_expression left: (identifier) right: (parenthesized_expression (binary_expression left: (identifier) right: (field_access object: (array_access array: (identifier) index: (identifier)) field: (identifier))))) right: (parenthesized_expression (binary_expression left: (field_access object: (array_access array: (identifier) index: (identifier)) field: (identifier)) right: (field_access object: (array_access array: (identifier) index: (identifier)) field: (identifier))))))))))) (expression_statement (assignment_expression left: (identifier) right: (identifier))))) (return_statement (identifier))))