for i = 1:6050,
dx(i)=X(i+1)-X(i);
dy(i)=Y(i+1)-Y(i);
end;
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A loop consists of
- the word "for", a counter variable (also called an index) which
must be an integer, and the limits of the loop. In this case
the loop will execute with i from 1 to 6050;
- a number of statements, which should be indented to help you
keep track of the bounds of the loop. In this case we are
filling vectors (or arrays) for dx and dy. We could do other
things, and use IF statements to vary our actions depending on the
specific values.
- we will be computing one value of the array/vector at a time,
and we explicitly say which one with the "(i)" notation. We do
not use the "." notation.
- the word "end" to indicate the end of the loop
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dx(1)=X(2)-X(1);
dy(1)=Y(2)-Y(1);
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First run through the loop:
- i is 1
- we compute dx(1) and dy(1), using the x and y values in the 1st
and 2nd positions
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dx(2)=X(3)-X(2);
dy(2)=Y(3)-Y(2); |
Second run through the loop:
- i is 2
- we compute dx(2) and dy(2), using the x and y values in the 2nd
and 3rd positions
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| ....... |
....... |
| dx(6050)=X(6051)-X(6050);
dy(6050)=Y(6051)-Y(6050);
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Last (6050th) run through the loop:
- i is 6050
- we compute dx(6050) and dy(6050), using the x and y values in
the 6050th and 6051st positions
- You must be careful, since this array will have 6050 values, but
the X and Y arrays used to compute it have 6051.
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