[MountainDew]

Does there happen to be any Matlab gurus out there? I'm taking a Matlab class and I have a project I'm supposed to complete that has me absolutely stumped. I don't necessarily want anyone to do this whole thing for me, but I would appreciate any hints and help you might be able to give me. The Matlab script has to do the following:

%%%%%Create a program that creates a countdown from a user-generated integer. If the number is negative, then the program should quit. If it's not, the program should then display the remaining time after every second of elapsed time. It should print "Blast off!" when the remaining time is zero and ask the user to input another number.%%%%%

I cannot figure this out and it's driving me crazy. Any help would be greatly appreciated!

[to_be_released]

Well, you've got a few main things to figure out. Firstly, you need user input, Request user input - MATLAB should help there.

Secondly you need to figure out the timer, have a look at Using a MATLAB Timer Object :: Program Scheduling (MATLAB®)

A simple while loop with a conditional statement along the lines of "while (number>=0)" should let you exit with negatives.

I'd perhaps suggest putting some form of rounding in, just in case the user puts in something that isn't an integer.

That should help you piece it together.

(by the way, google is a coders best friend. Todays help brought to you by Let me google that for you and Let me google that for you )

[bobthecockroach]

I don't know Matlab, but for something simple like this, I would look for a sleep/pause/wait statement rather than mess with a timer.

[to_be_released]

Good point Bob, pause appears to be the function to use (and it's use can actually be seen in the example for the timer that I linked above).

Something like

foo=10;
while(foo>0)
disp(foo)
foo=foo-1;
pause(1)
end
disp('Blast off!')

should work

[MountainDew]

Thanks a lot guys. Taking what to_be_released suggested, I added a few lab-specific things and came up with this.

function lab4program1

clc

disp('Welcome to the countdown timer program:');
time = input('Enter a time (seconds) or negative number to quit:');

if time < 0
disp('Time must be positive');
return
end


while time > 0
disp(time)
time = time - 1;
pause(1)
end

disp('Blast off!');
disp(' ');
disp('Thank you');

end

The lab says nothing about having to deal with non-integer inputs, so I'm not sure if I should do nothing, just have the input rounded, or display an error message if it's not an integer.

[bobthecockroach]

Spec says ask for another number, so you'll need to loop the whole thing too.

[MountainDew]

Originally Posted by bobthecockroach

Spec says ask for another number, so you'll need to loop the whole thing too.

Thanks, I missed that part. I've revised it to include that spec.

I took a look at the second part of the lab and it makes absolutely no sense to me. I am given a 6x5 matrix of 1s and 0s. I have to create a program that draws a red square if the number is a 1 and a red square if the number is zero. They give me a "template" for the code, but I can't make heads or tails out of it. Here's the template code they give me.

function lab4program2
level_map = [0 0 0 0 0;0 1 0 1 0;1 0 1 0 1; 0 1 0 1 0;0 0 1 0 0];
map_size = size(level_map);
a = axes();
axis(a,[0,6,0,6]);
hold on;
%your loop goes here
end
%draws a square on axes, a, at location x,y with radius r, and 3 element
%color, e.g. [0,0,1] for blue, or [1,0,0] for red
function draw_square(a,x,y,r,c)
plot([x-r,x-r,x+r,x+r,x-r],[y+r,y-r,y-r,y+r,y+r],'-','parent',a,'color',c);
end


Any help would be greatly appreciated guys!