# Jim Riggs

### Missile Defense Agency - Advanced Technology Group

Developing simulations for the Missile Defense Agency - Advanced Technology group

30+ years experience in missiles, smart munitions and other aerodynamic systems.

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**Content Feed**

How to connect the two signals in one signal in MATLAB Simulink? I mean first signal finishes second signal starts.

You description of the problem is confusing to me, bu the statement in the title "first signal finishes second signal starts" ...

7 months ago | 0

Numerical Integration in Matlab

There seem to be two problems: 1) your function "fun" returns "NaN" at zero, so you cannot integrate starting from zero. You n...

8 months ago | 0

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Simulink counter block having an initial starting value of -1

Yes, the two counter blocks in the library do not allow you to set the initial value. Whenever I need to use a counter, I usual...

8 months ago | 1

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Finding the roots of an equation using Newton-Raphson method but I don't know the equation!

You use a numerical approximation for the derivative. Start at some initial guess for x & y. take a small step, and compute th...

8 months ago | 1

Implementing Angles as an input in Simulink

It appears (based on the icon on the block) that the block labeled "Robot Controler" is a Matlab function block. In order to a...

9 months ago | 0

Pendulum using Runge Kutta

Yes, there are a few things wrong with this code. James Tursa has identified one obvious error. Another problem is with the lo...

9 months ago | 0

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How to return the index of time steps in Simulink?

One way to do this is to put a step counter in the block. This will keep track of the number of times the block is executed. T...

9 months ago | 0

Why is my code not working?

Not entirely sure if this is the reference in the error message, but this line has unballanced parentheses: f = (1/(t-t^(-1))*...

10 months ago | 0

SIR Simulink Model Function Block

In the Simulink library browser, on the "sources" pallet, you will find a "clock" function. Use this to create a time signal. ...

12 months ago | 0

How can one do this calculation?

Look into using logical indexing. Not my strong point, but for example, if A is the 3 x 10 matrix, you can select all cases whe...

1 year ago | 0

Kalman Filtering for smoothing GPS speed data

The problem is with this line: P = (1-KG)*P; This causes the gain P to continuously decrease. After a while, the gain P is ve...

1 year ago | 1

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numerical derivate and central difference

Here are some Numerical difference formulas using the central difference method (substitute dt = h). You can find more formulas...

1 year ago | 1

Meaning of the following: function [y1,...yn] = input()

It simply means that there are no user inputs to this function. The long list of variable names are returned from the function....

1 year ago | 0

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Angle Between two vectors.

Given two vectors A and B, the dot product of the two vectors (A dot B) gives the product ABcos(ang), so to get just the angle, ...

1 year ago | 0

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Is it possible to summarize this code?

You could use a switch case structure, that would be a bit more compact. it would look like this: switch davar1.CC_CHECK ...

1 year ago | 2

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help fixing the Heuns method

Heun's method is otherwise known as "explicit trapezoidal method", "improved Euler's method" or "modified Euler's method". Th...

1 year ago | 0

I need help coding a human cannonball ignoring air resistance

Assuming zero drag and relatively low muzzle velocity ( acceleration due to gravity = constant), the point-mass trajectory can b...

1 year ago | 1

Runge Kutta 4th Order Method

I think the problem is the T argument. in k1 you have a capital T, which is a 3-vector in k2, k3, and k4 it is a lower case t,...

1 year ago | 0

Matlab Homework that im struggling with

To prompt a user to enter a value, try: x = input('Enter the number of equations (from 2 to 5): \n')

1 year ago | 0

I need help with this script

Try this: T = input('Enter your temperature') if T<=96 disp('You are either hypothermic or a zombie') elseif T<99 d...

1 year ago | 0

Ballstic Impact of Bullets on armor

I don't know af any specific ballistics tools. You should browse the a list of Matlab products at this link: Matlab Products

1 year ago | 0

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How to find theta and theta dot in a simple pendulum simulation in MATLAB.

I'm not sure at all what your system equations are. The first rule of dynamics is where you have translational modes of motion ...

1 year ago | 0

What is a "system variable" in a Simulink model?

In this context, the "system" is the device that you are modelling. Therefore, a "system variable" is one of the variables in y...

1 year ago | 1

| accepted

Undefined function 'simset' for input arguments of type 'char'.

simset is an obsolete function. See documentation here. It says to use the Configuration Parameters dialog box.

1 year ago | 0

Newtons method for finding minimum of a function.

Here is another variation; function [f,g,h] = myfunction(x) f1 = @(z) exp(2*sin(z))-z; %function dx ...

1 year ago | 0

help me in trying to solve the secant method

Try preallocating x, right after you define n: n = 100; x = nan(1,n); ...

1 year ago | 0

trying to calculate the central diff approximation

There is a Matlab function "diff" which will do this. Otherwise, your subscripts must all match (2:end-1) Adi_1 = diff(Vdi_1...

1 year ago | 0

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Performing calculations (Newton's method) over values in loop

Yes, your loop is not quite right. Notice your placement of the three lines i=1; converge = false; po = p_init(1); These t...

1 year ago | 0

| accepted

Draw a circle for arbitrary orientation on spherical surface

My approach is to define the circle around the X-axis, then rotate it into the desired position through a Yaw-Pitch rotation. ...

1 year ago | 1

| accepted

the meaning of basic matlab words

an argument is a constant or variable that you provide to a function; e.g. sin(x) % here x is the argument to the function sin...

1 year ago | 0

| accepted