if statement didn't executed in a loop

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Shawn Chang
Shawn Chang 2012-12-13
Hi all, I have problem on the if statement that inside can't be executed which makes other operations in the code cannot be run. My code is as follow, the problems is occurred at the "if isequal(time(i),off_tt)" parts where the variables 'k' didn't increment.
k = 0; on_t = 2;off_t = 2;
for i=1:length(time)
on_tt = (on_t*(k+1))+(off_t*k)
off_tt = (on_t*(k+1))+(off_t*(k+1))
if(time(i) ~= off_tt)
if (on_t == 0)
ref_speed_left = [ref_speed_left, 0];
ref_speed_right = [ref_speed_right, 0];
elseif (off_t == 0)
ref_speed_left = [ref_speed_left, ref_speedR];
ref_speed_right = [ref_speed_right, ref_speedL];
elseif (time(i) < on_tt) %ans == 0
ref_speed_left = [ref_speed_left, ref_speedR];
ref_speed_right = [ref_speed_right, ref_speedL];
elseif (time(i)>= on_tt && time(i) < off_tt+1)
if isequal(time(i),off_tt) %problems at this if statement
k=k+1; %k didn't increment when it
end %met the requirement
ref_speed_left = [ref_speed_left, 0]
ref_speed_right = [ref_speed_right, 0]
end
end
end
May I know any solutions for this, your helps is much appreciate. Thanks you.
  2 个评论
Azzi Abdelmalek
Azzi Abdelmalek 2012-12-13
Can you post values of ref_speedR and others variables, to allow testing your code
Shawn Chang
Shawn Chang 2012-12-13
编辑：Shawn Chang 2012-12-13
time = 0.05:0.05:14.95;
ref_speedR = 0.3595;
ref_speedL = 0.3693;

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回答（3 个）

Ilham Hardy
Ilham Hardy 2012-12-13
for i=1:length(time)
k=i %correction
on_tt = (on_t*(k+1))+(off_t*k)
off_tt = (on_t*(k+1))+(off_t*(k+1))
You declare k=0, therefore k is 0.
  1 个评论
Shawn Chang
Shawn Chang 2012-12-13
"k=0" is used to initialize the k.
When on_tt and off_tt value has been met and k will be increment by 1 to obtain a new on_tt and off_tt.
eg. last value in time(i) = 15, on_t = 2, off_t = 2;
When k = 0; on_tt = 2, off_tt = 4;
When k = 1; on_tt = 6, off_tt = 8;
until either on_tt or off_tt reached 15, it will break the for loop.
So, "k=i" cannot be used in this case

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Azzi Abdelmalek
Azzi Abdelmalek 2012-12-13
编辑：Azzi Abdelmalek 2012-12-13
Are you sur the condition if isequal(time(i),off_tt) is true? I tested your code, the condition is true only for i=80
  8 个评论
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Shawn Chang
Shawn Chang 2012-12-13
I want to increment k when the element of time(i) is equal to off_tt, so that a new on_tt and off_tt will be obtained and the process run until the for loop is break.

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Roger Stafford
Roger Stafford 2012-12-13
Shawn, look at the third line from the beginning of the for-loop:
if(time(i) ~= off_tt)
It is an outer condition that must be satisfied if you are to enter the if-elseif-elseif-end sequence. This means you cannot reach the
if isequal(time(i),off_tt)
test with equal values of time(i) and off_tt. Hence the 'isequal' test will always be false and k can never be incremented.
I am curious as to why you used 'isequal' at that point. It is intended for testing equality between entire arrays and suggests that you may have meant something else in your code here.
Roger Stafford

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