# 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.

**Statistics**

RANK**158**

of 243,779

REPUTATION**582**

CONTRIBUTIONS

**4** Questions

**226** Answers

ANSWER ACCEPTANCE **
75.0%
**

VOTES RECEIVED**118**

RANK

of 17,054

REPUTATION**N/A**

AVERAGE RATING**0.00**

CONTRIBUTIONS**0** Files

DOWNLOADS **0**

ALL TIME DOWNLOADS**0**

CONTRIBUTIONS**0 Posts**

CONTRIBUTIONS**0** Public Channels

AVERAGE RATING

CONTRIBUTIONS**0** Highlights

AVERAGE NO. OF LIKES

**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" ...

10 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...

11 months ago | 0

| accepted

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...

11 months ago | 1

| accepted

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...

11 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...

11 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...

12 months ago | 0

| accepted

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...

12 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))*...

1 year 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. ...

1 year 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

| accepted

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

| accepted

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

| accepted

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

| accepted

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

| accepted

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

| accepted

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