Plotting a function with different conditions

am trying to build and plot a Triangular function with an amplitude of 1 , starting in second 1, reaching the max in second 3 and going back to zero in second 4,

x(A,t1,t2,t3,t) =

• A/t2-t1 *(t-t1), t1<=t<=t2
• A/t2-t3 *(t-t3),t2<=t< t3
• 0, elsewhere

the problem is that I can't find a way to add the two conditions to the function ,even with one condition I get only a straight line

here is what I got so far, please give me an idea to how to add them both

the script :

    fs = 20; %freq
      t = 0:1/fs:5;
    t1=1; t2=3;  t3=4;
    A=1; %amplitude

    x2 = mytri(A,t1,t2,t3,t);

     plot (t,x2,'.-')

     axis([ -2 5 -2 5])

the function

function x2 = mytri(A,t1,t2,t3,t)

 x2=A/t2-t1*t-t1*(t1<=t<=t2);

Answer 1

[Joseph Cheng]

Look at each portion of your mytri() function. (side note your x2 equation doesn't match the first condition for x (you're missing a t1^2. as t1*(t-t1)=t1*t-t1^2))

you can use the find() function to find when t1<=t and t<=t2. or use the x(t1<=t and t<=t2) to satisfy your conditions.

[wiig krist]

so using the find function will give me the ability to give x two values based on the condition ?! if not any ideas to do such a thing ? also why the ^2 I am multiplying with the amplitude A only ?

[Joseph Cheng]

yes what i suggested will get you to do your conditions for the sawtooth. next the condition

A/t2-t1 *(t-t1), t1<=t<=t2

means the equation when expanded for when t is between t1 and t2 is:

A/t2 - t1*t-t1*t1

what you have written in your function is:

A/t2 - t1*t-t1*(values of t between t1 and t2)

you need to follow the orders of operations as A*(B-C) is A*B-A*C and NOT A*B-C*(some subset of B or B itself)

[wiig krist]

Ok I got it , thanks