SYNTAX MATLAB

    y1 = x(2:n) ;
  t1 = n*dt - (2*dt:dt:n*dt)

could anyone tell me what is the meaning of the these commands? The syntax of MATLAB, I mean, what does do x(2:n) and n*dt - (2*dt:dt:n*dt) ? x times (2:n)? and the second one sub an 4 dimension array from a scalar ?

Answer 1

[Thomas]

Eg.

x=1:20;   %i.e x=1 2 3.... 20
n=5;    % assign value of 5 to n
y1 = x(2:n)   % get second to nth (5th )value in x and put it in y1

Output of above

 y1 =
            2.00          3.00          4.00          5.00

 dt=1; %assign value of 1 to dt.. you can give any value

 t1 = n*dt - (2*dt:dt:n*dt);

frist term n*dt %multiply n (scalar) by dt a scalar

n*dt
ans =
          5.00

second term 2*dt:dt:n*dt % range twice dt to ntimes dt witht a difference of dt for above case 2*1:1:5*1 i.e (2:1:5)

2*dt:dt:n*dt
ans =
          2.00          3.00          4.00          5.00

ti=sub first term (scalar) -second term (array) (5-2, 5-3, 5-4, 5-5)

t1 = n*dt - (2*dt:dt:n*dt)
t1 =
          3.00          2.00          1.00             0

[Sara]

what is the type of x, here? what is the meaning of dt in (2*dt:dt:n*dt)