Error in dfdt (line 3)

Unable to run my function even though my textbook was able to get it done this way...

even when I put the value of fs in, it still gives errors...

[Walter Roberson]

When you run your function by pressing the green Run button, where are you expecting MATLAB to look for values for z?

[Roos]

I was asked to test dfdt using the test signal: and check if the plotted signal resembles the analytically obtained derivative of z(t) = sin(2*pi*f*t).

Answer 1

[Torsten]

The code line in the loop must read

za(i) = (z(i+1)-z(i-1))/(2*h)

instead of

za(i) = (z(i+1)-(i-1))/(2*h)

And call the function with reasonable inputs, e.g.

x = 0:0.1:1;
z = sin(x);
fs = 10;
za = dfdt(z,fs)
plot(x,za)