Help with Summation in Matlab

Hi guys i have the follwoing code that I am stuggling to get running.

Any help would be appreaciated?

% The Given Data

x_1=4;      %Assign Initial Values of x
y_1=0;       %Assign Initial Values of y
t_j =Data(:,1);     %assign Values of t
V_xj= Data(:,2);    %Assign Values of V_xj
V_yj= Data(:,3);    %Assign Values of V_yj
k = (1:4);
syms(1j)
x_k= symsum(V_xj(t_j+1 - t_j)+x_1,1i,1,k-1);    %Calculate values of x_k
y_k= symsum(V_yj(t_j+1 - t_j)+y_1,1i,1,k-1);    %Calculate values of y_k

[Matt J]

What's it supposed to do and what kind of variable is Data (single, double,sym,...)?

[Walter Roberson]

My guess is that

x_k = symsum(V_xj(t_j+1 - t_j)+x_1,1i,1,k-1)

is intended to represent

[Adrian Rodgers]

correct walter

Answer 1

[Walter Roberson]

My guess:

x_k = sum(diff(t_j(1:k)) .* V_xj(1:k-1) + x_1);

but the x_1 does not make sense to me in that location: why would you want to add it for each k value?

... When k = 1, is x_k intended to refer to the same place thing as x_1 ?

[Adrian Rodgers]

thanks Walter x_1 is the intial location.

[Walter Roberson]

It would make more sense to me if you were adding instead of -- though in that case you would have to work iteratively.

It looks to me as if can be created from as