# Paul

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**Content Feed**

want to differentiate 1+c*exp(t)/1-exp(t) which is 2*c*exp(t)/(1-exp(t))^2 and then return it to it's original form by integration using int(), understand rewrite(tanh,"exp")

Hi Joseph, I think you got the correct result, though not using what might be considered best practices syms f c t y(t) y ypri...

2 days ago | 0

Problem with using mussv

Hi Ofek, N = 30; w_vec = logspace(-5,5,100); "I calculate it using the function freqresp and the resulting array has dimensio...

3 days ago | 0

| accepted

Question

What Does the Symbolic Math Toolbox Mean by 0 < s When s is Complex?

syms s syms t real f = int(exp(-s*t),t,-inf,0) What does that first condition mean insofar as s is complex?

4 days ago | 1 answer | 0

### 1

answerQuestion

Does the Symbolic Toolbox Support 0- and 0+ ?

syms s syms t real f = int(exp(-s*t),t,-inf,0) Is the second term in the second condition a notation for (though I'm not e...

4 days ago | 1 answer | 0

### 1

answerAdjusting a Sawtooth Graph and getting spectrum

Do you want a triangle or a sawtooth? Assuming the former as stated in the question, use tripuls %T = 10*50; fs = 2000; t = ...

4 days ago | 0

| accepted

how to find Laplace transform of u(-t) in MATLAB?

Hi Sundaram, The function laplace implements the unilateral Laplace transform for causal signals. However, heaviside(-t) is no...

4 days ago | 0

| accepted

How can a Simulink State Space block state be periodically reset?

i think you'll have to use an Integrator and other native blocks to implement xdot = A*x + B*u y = C*x + D*u Use the external...

5 days ago | 0

modred() Scaled Output

Hi Sam, I can't explain why TMW chose to change the behavior of modred. Having said that, I have some observations about your ...

6 days ago | 0

| accepted

How to get 2% and 5% settling time from simulink?

Hi Daniel, I'm interpreting your question to mean that you have a Simulink model of the system and in Simulink you stimulate th...

7 days ago | 0

Zero-order hold practical differentiator offsets magnitude

Hi Greg, I don't know if this will be the complete explanation your looking for, but here goes .... Define the continuous-time...

10 days ago | 0

| accepted

Symbolic integration has 3 solutions based on integration variable range, how to extract one of these?

syms U_0 r Radius mom_2 = int((U_0*(1-r/Radius)^(1/7))^2*2*sym(pi)*r,r,0,Radius) One approach that just extracts the case you ...

11 days ago | 2

| accepted

How to set the sample time of a discrete transfer function block to 0.005? Please tell

Hi ISHITA, TMW recommends leaving the sample time of that block as inherited. Instead, control the sample time of the signal th...

12 days ago | 0

| accepted

Discrete-time Simulink not matching Matlab Connect()

Hi John, Check this comment for an example that shows the same open loop system obtained from the combination of connect and ge...

13 days ago | 0

Do source blocks in Simulink have an implicit unit step function built into them?

For the top path: Y(s) = s/(s+1)*X(s) = 1/(s+1) * (s*X(s)) The differentation rule for the one-sided Laplace transform is: L(...

13 days ago | 1

| accepted

Find the 3D components-based row of an array that most closely matchs a given vector

I think the specific solution would depend on the figure of merit for defining "closeness" of two vectors. For example, if the ...

14 days ago | 0

Why are subsystems highlighted in different color after simulation

Hi Neelabh, It looks like it might be due to Sample Time Colors. Go to Debug -> Information Overlays and see if the Sample Time...

15 days ago | 0

| accepted

Execute Matlab function in Simulink

You are correct. In Matlab, the code looks like this (actually making the call to moving_average2) t = 0:0.1:10; u = sin(t); ...

16 days ago | 0

| accepted

why am i getting the error "Incorrect number or types of inputs or outputs for function step."

Hi Salim Your code runs fine here. What version of Matlab are you using? I just changed the code to make separate plots intead...

16 days ago | 0

ifft convert frequency domain to time domain

Hi Angie, The input to ifft should cover all frequencies from 0 to Fs - df, where df is the frequency step. In this case, max(f...

16 days ago | 1

| accepted

How to automatically reinitialize the model workspace when Run Simulink model

Hi Steven, Model workspaces can be manipulated programatically In your workflow, create a model workspace object and use reloa...

18 days ago | 0

| accepted

Symbolic expressions with pi are displaying as decimals

Hi Nathaniel. Option 1: Always use sym(pi); in symbolic expressions. For example 5.13445677*sym(pi) If you use the numeric ...

19 days ago | 1

Why does augw(P, W1, W2, W3) give a much lower order generalized plant when compared to the by hand construction?

Hi Vinh, The 'by-hand' construction is nearly certainly not what augw actually does. You can look at the augw code; maybe it wi...

21 days ago | 1

| accepted

How to use freqz to plot the frequency response from neg frequency to pos frequency

Use the third argument to freqz to specify the desired frequency points: f_sampling = 40e3; % sampling frquency f_pass = 10e3;...

22 days ago | 0

Need help substituting vector variables into symbolic expression

syms x y Option 1. Use a symbolic function z(x,y) = x + y z([1 2],[100 200]) Option 2. Symbolic expression, subs with a cell...

25 days ago | 0

Discrete Derivative block (Simulink) behaves differently than expected

Hi John, How did you get the yellow colors on the rate transition blocks on the signals coming out of those? If you turned on ...

26 days ago | 0

Matlab is not giving the correct z transform of - (n*a^n)*u[- n - 1];

In addition to what @VBBV said about a typo in the defintion of y[n], there are two other fundamental problem that needs to be a...

29 days ago | 1

Fourier transform of derivative expression with respect to time

Hi Erikan, I'm not clear what you're asking about how j*w should be calculated. It's just part of the expression. If you're as...

30 days ago | 0

What's the difference between two command?

That's the old, obsolete form of nyquist() that was used for state space models before the Control System Toolbox introduced lti...

1 month ago | 2

Question

What is the Distinction Between Answers and Discussions?

I just now discovered Discussions. Can anyone provide insight into the intended difference between Discussions and Answers and ...

1 month ago | 3 answers | 2

### 3

answersGiven an LTI system with corresponding transfer matrix K(s), is there an easy way to specify K(w) where w=s+delta?

Hi Vinh, I think the substitution backward. It should go like this: K(s) = C * inv(s*I - A) * B + D w = s + delta -> s = w ...

1 month ago | 0