How do you change the value of a subfunction variable?

I have a subfunction called loanPayment that I want to have a specific value.

To specify: loanPayment is a function containing the inputs (P,r,n_t,R) and the output (A). However, in my function, I want to use the same loanPayment function to calculate output(1) but with a value of 100+min payment instead of R.

I apologize if this is a stupid question but I have looked around already and am not completely convinced with my search results.

The following is my code:

function [ output ] = studentLoan( P,r,n_t )

%Calculates the metrics of a loan

%   P: principle value of the loan

%   r: interest rate

%   n_t: the number of payments at which we assess the value of the loan

%   output(1): the amount left in the loan if $100 more than the minimum

%       payment is made every compounding period after n_t periods and every

%       payment is made

%   output(2): the minimum payment needed to prevent the loan from growing

output=zeros(1,5);

output(1)=??????;

output(2)=@minPayment;

      function [ R ] = minPayment(P,r,n_t)
         % calculates minimum payment needed to prevent the loan from growing
          R=(P*(1+r).^n_t)/symsum((1+r)^k,k,0,n_t-1);
      end
      function [ num ] = timeToPay (P,r,R)
          % Calculates how many payments it would take to pay off the loan
          %   given a rate of payment R
              % num = number of payments     
      end
  end

function [ A ] = loanPayment( P,r,n_t,R)

A=evalPoly([P,-R*ones(1,n_t)],[n_t:n_t-1],1+r);

end

Answer 1

[Walter Roberson]

You can call the function with different arguments:

value1 = .....
output1 = loanPayment( P, r, n_t, value1);
output2 = loanPayment( P, r, n_t, 100+value1);