Consider the definition: function [s1, s2, sums] = sines(pts,amp,f1,f2). The input, pts, is an integer, but amp, f1, and f2 and are not necessarily integers. Output argument s1 is a row vector whose length (number of elements) equals pts. The elements of s1 are the values of the sine function when it is given equally spaced arguments that start at zero and extend through f1 periods of the sine. (Note that we ask for full periods, so if f1 is an integer, both the first and the last element of s1 will be 0 other than a very small rounding error.) The amplitude of the sine wave equals amp. The vector s2 is the same as s1 except that s2 contains f2 periods. The vector sums is the sum of s1 and s2. If f2 is omitted, then it should be set to a value that is 5% greater than f1. If f1 is omitted also, then it should be set to 100. If amp is not provided, then it should default to 1. Finally, if pts is omitted as well, then it should be set to 1000. For example, if you run sines without any input arguments and then you plot the third output argument, sums, the figure should look like this (if you stretch the plot window horizontally):

Answer

function [s1 s2 sums] = sines(pts,amp,f1,f2)

if nargin

if nargin

if nargin

if nargin

t = 0 : 2*pi/(pts-1) : 2*pi;

s1 = amp * sin(f1*t);

s2 = amp * sin(f2*t);

sums = s1 + s2;

end

 

% The sin() function has a full period between 0 and 2*pi.

% To set up the vector t, dividing by (pts-1) is needed

% because n points in a line define (n-1) consecutive segments

% and not n. For example, two points define a single line segment.

% The function call sin(f1*t) will create exactly f1 full periods

% using vector t defined above.