Function inside my function

Question

Gerenimo 2016-4-29

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/281732-function-inside-my-function

回答： Jan 2017-1-31

I have two function on my m. file, function "VaR" and "VanDerCorput", "VanDerCorput" function required on "VaR" function, how to run VaR function but also with VanDerCorput function run too? this is my code :

   function VaR=MC(NbTraj,p,alpha)
   %Function computing the value at risk of a
   %portfolio composed of two bonds.
   NbTraj= 50000; %Number of simulations.
   p= 0.5; %Weight for each bond.
   alpha= 0.96; %Confidence level
   %Identification of our data file
   fid=fopen('SpotRates.txt','rt');
   %Reading of the data from file SpotRates.txt
   Data=fscanf(fid, '%f %f %f %f %f %f %f %f %f');
   %Closing of source file.
   fclose(fid);
   %Partition of data into date and different rates
   M1=Data(1:9:size(Data));   %spot rate 1 month
   M3=Data(2:9:size(Data));   %spot rate 3 months
   M6=Data(3:9:size(Data));   %spot rate 6 months
   Y1=Data(4:9:size(Data));    %spot rate 1 year
   Y2=Data(5:9:size(Data));    %spot rate 2 years
   Y3=Data(6:9:size(Data));    %spot rate 3 years
   Y5=Data(7:9:size(Data));    %spot rate 5 years
   Y10=Data(8:9:size(Data));  %spot rate 10 years
   Y30=Data(9:9:size(Data));  %spot rate 30 years
   %Matrix of rates
   Data1=[M1,M3,M6,Y1,Y2,Y3,Y5,Y10,Y30];
   %Initial rates
   ActualRates=Data1(size(Data1,1),:);
   %Normalization of rates
   for i=1:9
      Average(i)=mean(Data1(:,i));
      Deviation(i)=std(Data1(:,i));
      Data1(:,i)=(Data1(:,i)-Average(i))/Deviation(i);
   end
   %The standard deviation for a one month period.
   %We want a value at risk for 10 days and we divide by
   %sqrt(3) since 1 month = 3*10 days.
   Deviation=Deviation/sqrt(3);
   %Eigenvectors and eigenvalues of the covariance matrix
   %Vector -Vi can also be returned by function
   %eigs if Vi is an eigenvector.
   [V,E]=eigs(cov(Data1),3);
   %Components determination.
   PC1=V(:,1);
   PC2=V(:,2);
   PC3=V(:,3);
   %Graph of the principal components.
   plot((1:1:9),sqrt(E(1,1))*PC1,'r',(1:1:9),sqrt(E(2,2))*PC2,'b',...
        (1:1:9),sqrt(E(3,3))*PC3,'m');
   Weight1=p;
   Weight2=1-Weight1;
   %Initial parameters
   CouponRate1=0.06;
   FaceValue1=1000;
   CouponRate2=0.08;
   FaceValue2=1000;
   coupon1=CouponRate1*FaceValue1;
   coupon2=CouponRate2*FaceValue2;
   %Vectors for quasi random variables
   u1=zeros(NbTraj,1);
   u2=zeros(NbTraj,1);
   %Simulation of quasi random numbers
   for l=1:NbTraj
      u1(l)=norminv(VanDerCorput(l,3));
      u2(l)=norminv(VanDerCorput(l,5));
   end
   %Spot rates matrix
   Rates=zeros(9,NbTraj);
   %Loop generating the interest rates
    for j=1:NbTraj
      for i=1:9
           %Computation of rates. We multiply by the sign of the first
           %element of the components to fix them positively. This will allow
           %us to replicate perfectly our results if needed.
           Rates(i,j)=ActualRates(1,i)+...
            Deviation(i)*(sqrt(E(1,1))*u1(j,1)*V(i,1)*sign(V(1,1))+...
            sqrt(E(2,2))*u2(j,1)*V(i,2)*sign(V(1,2)));
      end
    end
   %Spot rates initial values
   M6=ActualRates(1,3);   %spot rate 6 months
   Y1=ActualRates(1,4) ;  %spot rate 1 year
   Y2=ActualRates(1,5);   %spot rate 2 years
   Y3=ActualRates(1,6);   %spot rate 3 years
   Y5=ActualRates(1,7);   %spot rate 5 years
   %Linear interpolation
   Y1_5=(Y1+Y2)/2;        %spot rate 1.5 years
   Y2_5=(Y2+Y3)/2;        %spot rate 2.5 years
   Y3_5=(3*Y3+Y5)/4;      %spot rate 3.5 years
   Y4=(Y3+Y5)/2;          %spot rate 4 years
   Y4_5=(3*Y5+Y3)/4;      %spot rate 4.5 years
   %Determination of initial bonds' prices.
   price1=(coupon1/2)/(1+(M6/100))^(1/2)+(coupon1/2)/(1+(Y1/100))^1+...
        (coupon1/2)/(1+(Y1_5/100))^(3/2)+(coupon1/2)/(1+(Y2/100))^2+...
        (FaceValue1+(coupon1/2))/(1+(Y2_5/100))^(5/2);
   price2=(coupon2/2)/(1+(M6/100))^(1/2)+(coupon2/2)/(1+(Y1/100))^1+...
        (coupon2/2)/(1+(Y1_5/100))^(3/2)+(coupon2/2)/(1+(Y2/100))^2+...
        (coupon2/2)/(1+(Y2_5/100))^(5/2)+(coupon2/2)/(1+(Y3/100))^3+...
        (coupon2/2)/(1+(Y3_5/100))^(7/2)+(coupon2/2)/(1+(Y4/100))^4+...
        (coupon2/2)/(1+(Y4_5/100))^(9/2)+...
        (FaceValue2+(coupon2/2))/(1+(Y5/100))^5;
   %Portfolio's initial price.
   InitialPrice=Weight1*price1+Weight2*price2;
   %Loop computing the possible evolution of the portfolio's price.
   for k=1:NbTraj
      M6=Rates(3,k);    %Spot rate 6 months
      Y1=Rates(4,k);    %Spot rate 1 year
      Y2=Rates(5,k);    %Spot rate 2 years
      Y3=Rates(6,k);    %Spot rate 3 years
      Y5=Rates(7,k);    %Spot rate 5 years
      Y1_5=(Y1+Y2)/2;       %Spot rate 1.5 years
      Y2_5=(Y2+Y3)/2;       %Spot rate 2.5 years
      Y3_5=(3*Y3+Y5)/4;     %Spot rate 3.5 years
      Y4=(Y3+Y5)/2;         %Spot rate 4 years
      Y4_5=(3*Y5+Y3)/4;     %Spot rate 4.5 years
      %Valuation of two different bonds
      price1n=(coupon1/2)/(1+(M6/100))^(1/2)+(coupon1/2)/(1+(Y1/100))^1+...
            (coupon1/2)/(1+(Y1_5/100))^(3/2)+(coupon1/2)/(1+(Y2/100))^2+...
            (FaceValue1+(coupon1/2))/(1+(Y2_5/100))^(5/2);
      price2n=(coupon2/2)/(1+(M6/100))^(1/2)+(coupon2/2)/(1+(Y1/100))^1+...
            (coupon2/2)/(1+(Y1_5/100))^(3/2)+(coupon2/2)/(1+(Y2/100))^2+...
            (coupon2/2)/(1+(Y2_5/100))^(5/2)+(coupon2/2)/(1+(Y3/100))^3+...
            (coupon2/2)/(1+(Y3_5/100))^(7/2)+(coupon2/2)/(1+(Y4/100))^4+...
            (coupon2/2)/(1+(Y4_5/100))^(9/2)+...
            (FaceValue2+(coupon2/2))/(1+(Y5/100))^5;
   %Computation of the portfolio's price for this scenario
   PortfolioPrice=Weight1*price1n+Weight2*price2n;
   vectPrice(k,1)= PortfolioPrice;
   end
   %Sorting the prices and VaR computation.
   vectPrice=sort(vectPrice);
   VaR=(InitialPrice-vectPrice(floor(alpha/100*NbTraj)));
   vectprice1(k,1)=price1n;
  end 
function rep=VanDerCorput(n,b)
 %Function generating the Van Der Corput sequence to build Halton sequence.
 n=100; %Index of the sequence of elements.
 b=2; %Basis for decomposition.
 bn=0;
 j=0;
  while n~=0
    bn=bn+mod(n,b)/b^(j+1);
    n=floor(n/b);
    j=j+1;
  end
 rep=bn;
end

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Answer 1

Jan 2017-1-31

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在 MATLAB Online 中打开

You have different possibilities:

Store both functions in the same file. Set the main function, which is called from the outside on top.
Store the subfunction in an own M-file. Then it is called from your function, but can be called from any otehr function also.
Define the subfunction inside the main function. This is called "nested function" and you can share variables with the caller. A nested function can be called from inside the caller only.
Create an own M-file for the subfunction and store it in the subfolder \private. Then all functions in the folder of the main function can call the subfunction, but it is hidden for all other functions.

The easiest way would be to copy the complete text as shown above in one M-file. Pleasesearch in the documentation for more details about functions also:

docsearch function

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Function inside my function

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