function [rv1 rv2]= myfunction(fcn, v, s)
% fcn is the function passed in
%for loop:
	for i = 1:length(v)
	  rv1(i) = v(i) + i;
	end

	k=1;

%while loop:
	while k<5
		%formatted printing:
		fprintf("k = %d\n",k)
		k++;
	end

	fprintf("Third argument is %f\n",s);

%if statement ( options: >= <= == ~=
	if k > 2
		fprintf("Inside if statement...\n");
	end
	
%applying function to whole array:
	rv1 = fcn(v);

%operation element by element: (.* ./ .+ etc...)
	rv2 = 2 .^v;

%reading a variable interactively:
	x = input("Enter a number:");
	fprintf("2 x input = %f\n",2*x);

%opening a file for write:
	fid = fopen('mydata.dat', 'w');
	if fid < 0
		fprintf('Could not open  file to write');
		return;
	end

	for i=1:10
		fprintf(fid,"%d %d %d\n", i,i^2,i^3);
	end
	fclose(fid);

%opening a file for read:
	fid = fopen('mydata.dat','r');
	for i=1:3
		fscanf(fid,'%d %d %d');
	end
	fclose(fid)

%reading a matrix using load
	B=load('A.mat')
	X=B(:,1);
	Y=B(:,2);
	fitY=zeros(length(Y),1);

%calling another function that computes the nth order polynomial fit to data:
	params=nthpoly(3,'A.mat');
	for j=1:length(params)
		fitY += params(j)* X .^ (j-1);
	end

%plotting in matlab/octave:
	clf; hold on;
	plot(X,Y, '.+r');
	plot(X,fitY,'-c');
	legend('a+bx+cx2+dx3','location','north');
	xlabel('x');
	ylabel('y');
	title('Fit to third order polynomial');

%creating a hard copy in a .ps file:
	print('plot.ps','-depsc');
	
end