Question about the error "Attempted to access (0.5); index must be a positive integer or logical."

I created matlab code in m file like below

D_s = 0.6;

T_d = 0.2;

T_c = 0.5;

x_sd = 0.5*D_s;

x_ed = 0.5*D_s;

g = 9.8;

z = 0.9;

m = 40;

for k = 1:1:10

      for t = k*T_c:0.1:(k*T_c)+T_d

          x_h(t) = k*D_s+(x_ed*(T_d+k*T_c-t)/T_d)+((D_s-x_sd)*(t-k*T_c)/T_d);

      end

      for t = k*T_c+T_d:0.1:(k+1)*T_c

          x_h(t) = k*D_s+(D_s-x_ed*((k+1)*T_c-t)/T_c-T_d)+((D_s+x_ed)*(t-k*T_c-T_d)/T_c-T_d);

      end

end

for t = k*T_c:0.1:(k+1)*T_c

      p_x = x_h(t)-(g/z)*diff(diff(x_h(t)));

      F_gr = m*(diff(diff(x_h(t)))-g);

end

After writing this code, I ran this m file, but no results came out. Only the error came out

Attempted to access (0.5); index must be a positive integer or logical.

Error in CoMtraj (line 11)
        x_h(t) = k*D_s+(x_ed*(T_d+k*T_c-t)/T_d)+((D_s-x_sd)*(t-k*T_c)/T_d);

What should I change in this code? I should observe the continuous function x(t) with respect to the time variable t

Answer 1

[Walter Roberson]

Change your loops. For example where you have

      for t = k*T_c:0.1:(k*T_c)+T_d

          x_h(t) = k*D_s+(x_ed*(T_d+k*T_c-t)/T_d)+((D_s-x_sd)*(t-k*T_c)/T_d);

      end

change it to

      tvals = k*T_c:0.1:(k*T_c)+T_d;
      for tidx = 1 : length(tvals);
          t = tvals(tidx);
          x_h(tidx) = k*D_s+(x_ed*(T_d+k*T_c-t)/T_d)+((D_s-x_sd)*(t-k*T_c)/T_d);
      end