% Solutions for problem set 1, EN 74, Fall 2007

% CREATING VARIABLES
% Problem 1
a = 1
b = -2
c = -5.5
d = 7

% Problem 2
s = a+b+c+d
p = a*b*c*d

% Problem 3
clear a b c
whos

% PERFORMING CALCULATIONS
% Problem 4
sc = -1.3
vct = [1;2;3]
mtx1 = [1 2 3 ; 4 5 6 ; 7 8 9]
mtx2 = [1 2 3 ; 1 2 3; 1 2 3]

% Problem 5
sc*vct

% Problem 6
mtx1*vct

% Problem 7
mtx1*mtx2

% Problem 8
mtx1.*mtx2

% Problem 9
mtx1(:,1).^vct

% Problem 10
time = -1:.01:1
lt = length(time)
% We have 201 points in time since we include both "ends" i.e., 1 and -1 in
% the vector

% Problem 11
t = linspace(-1,3,2000);
y = sin(10*t) .* cos(20*t).^2 .* exp(-9*t/10);
plot(t,y);xlabel('time');ylabel('y(t)')

% Problem 12
x = linspace(-1,1,50);
y = x;
[X Y] = meshgrid(x,y);
f = X.^2 .* (1-Y).^3 .* (1+abs(X)).^(-1);
mesh(x,y,f)
xlabel('x');ylabel('y');zlabel('f')


% Problem 13
imagesc(x,y,f)
xlabel('x');ylabel('y');zlabel('f')

% Problem 14
% This is the script