%% Price a 1-Year Call Swaption Using an HJM Interest-Rate Tree
% This example shows how to price a 1-year call swaption using an HJM interest-rate tree. Assume that interest rate is fixed at 5% annually between the valuation date of the tree until its maturity. Build a tree with the following data.

Rates = [ 0.05;0.05;0.05;0.05];  
StartDates = 'jan-1-2007';  
EndDates =['jan-1-2008';'jan-1-2009';'jan-1-2010';'jan-1-2011'];
ValuationDate = StartDates;  
Compounding = 1;    

% define the RateSpec
RateSpec = intenvset('Rates', Rates, 'StartDates', StartDates, 'EndDates',...
EndDates, 'Compounding', Compounding);   

% use VolSpec to compute the interest-rate volatility
VolSpec=hjmvolspec('Constant',0.01);

% use TimeSpec to specify the structure of the time layout for the HJM interest-rate tree
TimeSpec = hjmtimespec(ValuationDate, EndDates, Compounding);

% build the HJM tree
HJMTree = hjmtree(VolSpec, RateSpec, TimeSpec); 

% use the following swaption arguments
ExerciseDates = '01-Jan-2008';
SwapSettlement = ExerciseDates;
SwapMaturity   = 'jan-1-2010';
Spread = [0];  
SwapReset = 1;   
Basis  = 1;  
Principal = 100;  
OptSpec = 'call';    
Strike=0.05;   

% price the swaption

[Price, PriceTree] = swaptionbyhjm(HJMTree, OptSpec, Strike, ExerciseDates, ...
Spread, SwapSettlement, SwapMaturity,'SwapReset', SwapReset, ...
'Basis', Basis, 'Principal', Principal)

% Copyright 2015 The MathWorks, Inc.