agent.m

人工智能的matlab程序

// CLASS METHODS
// +setWorld: (World *)aWorld



#import "Agent.h"

World * worldForAgent;

@implementation Agent
/*" This is the abstract superclass of all agent classes; all agent classes
// must be direct or indirect descendants of this one.
"*/


/*" Sets a world for an agent.  It is a class method as it is used in
both class and instance methods in BFagent."*/
+setWorld: (World *)aWorld;
{
  worldForAgent = aWorld;
  return self;
}

/*" Gives an integer name to an agent during creation. Sometimes it
 * helps with debugging to have a unique id for each agent "*/
-setID: (int)iD
{
  myID = iD;
  return self;
}


/*" Sets the agent's position (holding) to "aDouble"."*/
-setPosition: (double)aDouble
{
  position = aDouble;
  return self;
}


/*"  Sets the IVAR intrate and uses that to calculate intratep1 (intrate + 1)."*/
-setintrate: (double)rate;
{
  intrate = rate;
  intratep1 = intrate + 1.0;
  return self;
}


/*" Sets the borrowing and short selling constraints, i.e., the 
  //      values can be negative. It sets values of the IVARS minholding and mincash"*/
-setminHolding: (double)holding   minCash: (double)minimumcash
{
  minholding = holding;
  mincash = minimumcash;
  return self;
}

/*" Sets the initial cash holdings of each agent."*/
-setInitialCash: (double)initcash;
{
  initialcash = initcash;
  return self;
}

/*" Sets the initial stock holdings of each agent. It is the
 * designated initializer.  Most agent classes will have additional
 * initialization, but should do [super setInitialHoldings] to run
 * this first. It will initialize instance variables common to all
 * agents, setting profit,wealth, and position equal to 0, and it sets
 * the variable cash equal to initialcash "*/
-setInitialHoldings
{
  profit = 0.0;
  wealth = 0.0;
  cash = initialcash;
  position = 0.0;

  return self;
}

/*" Sets an instance variable of agent, price, to the current price
  which is controlled by the object known as "world". Please note this
  assumes world is already set. "*/
-getPriceFromWorld
{
  price = [worldForAgent getPrice];
  return self;
}

/*"Sets an instance variable of agent, dividend, to the current dividend. That information is retrieved from the object known as "world"."*/
-getDividendFromWorld
{
  dividend = [worldForAgent getDividend];
  return self;
}


-creditEarningsAndPayTaxes
/*"Sent to each agent after a dividend is declared.  The agents
 * receive the dividend for each unit of stock they hold.  Their cash"
 * in the fixed asset account also receives its interest.  Then taxes
 * are charged on the previous total wealth, at a rate that balances
 * the interest on cash -- so if the agent had everything in cash it
 * would end up at the same place.

 * This is done in each period after the new dividend is declared.  It is
 * not normally overridden by subclases.  The taxes are assessed on the
 * previous wealth at a rate so that there's no net effect on an agent
 * with position = 0.
 *
 * In principle we do:
 *	wealth = cash + price*position;			// previous wealth
 *	cash += intrate * cash + position*dividend;	// earnings
 *	cash -= wealth*intrate;				// taxes
 * but we cut directly to the cash:
 *	cash -= (price*intrate - dividend)*position
" */
{
  [self getPriceFromWorld];
  [self getDividendFromWorld];
  
// Update cash
  cash -= (price*intrate - dividend)*position;
  if (cash < mincash) 
    cash = mincash;
  
// Update wealth
  wealth = cash + price*position;
  
  return self;
}


-(double)constrainDemand: (double *)slope : (double)trialprice
/*" Method used by agents to constrain their demand according to the
 * mincash and minholding constraints.

 * It checks "demand" against the
 * mincash and minholding constraints and clips it if necessary, then
 * also setting *slope.  For use within subclass implementations of
 * getDemandAndSlope: forPrice:.  Used only by agents that work with
 * the Slope Specialist."*/

{
// If buying, we check to see if we're within borrowing limits,
// remembering to handle the problem of negative dividends  -
// cash might already be less than the min.  In that case we
// freeze the trader.
  if (demand > 0.0) {
    if (demand*trialprice > (cash - mincash)) 
      {
	if (cash - mincash > 0.0) {
	  demand = (cash - mincash)/trialprice;
	  *slope = -demand/trialprice;
	}
	else 
	  {
	    demand = 0.0;
	    *slope = 0.0;
	  }
      }
  }

// If selling, we check to make sure we have enough stock to sell
  else if (demand < 0.0 && demand + position < minholding) 
    {
      demand = minholding - position;
      *slope = 0.0;
    }
  return demand;
}

/*" Return the agent's current position "*/
-(double)getAgentPosition
{ 
  return position;
}

/*" Return the agent's current wealth "*/
-(double)getWealth
{
  return wealth;
}


/*" Return the agent's current cash level "*/
-(double)getCash
{
  return cash;
}

/*"Sent to each enabled agent at the start of each trading period,
 * before the first -getDemandAndSlope:forPrice: message for that
 * agent.  The class method +prepareForTrading: is sent to each type
 * before any of these messages.  This probably should have some
 * subclassMustImplement code here, because the default code does
 * nothing. It must be overridden"*/
-prepareForTrading
{
  return self; 
}

/*" This message is sent to each agent during bidding to ask for its bid
//	(demand > 0) or offer (demand < 0) at price p.  The agent may
//	also return a value for d(demand)/d(price) through "slope",
//	but this is not required; *slope may be left unchanged.  This
//	method may be called one or more times in each period,
//	depending on the specialist method.  The last such call is at
//	the final trading price.  The -prepareForTrading message is
//	sent to each agent before the first such call in each period.
//	Note that agents without demand functions return zero slope,
//	but the Slope specialist is never used with these agents.
//
//	There is no default for this method in the Agent class; the
//	agent subclasses MUST provide it."*/

-(double)getDemandAndSlope: (double *)slope forPrice: (double)p
{
  [self subclassResponsibility:_cmd];
  return 0.0;		// not reached
}

/*"Sent to each enabled agent at the end of each period to tell it to
  // update its performance meaures, forecasts, etc.  The default code
  does nothing, this method must be specified by each agent type.
  Probably needs a subclass responsibility statement"*/
-updatePerformance
{
  return self;	
}


@end