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Jim Riggs


Missile Defense Agency - Advanced Technology Group

184 total contributions since 2017

30+ years experience in missiles, smart munitions and other aerodynamic systems. Specializing in systems engineering, aerospace systems design, simulation and modeling, aerodynamics, and numerical analysis.
Currently developing simulations for the Advanced Technology group of the Missile Defense Agency

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Question


What is the best way to insure that all of my functions are using the same constant values?
I want to make sure that my functions are all using the same values for physical constants, like earth radius, elipsoidal flatte...

3 days ago | 2 answers | 0

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Why will these plots not plot on the same graph?
You need to turn on "hold" mode to plot more than one plot on the same axes. If you do not use hold, the next plot replaces the...

5 days ago | 0

Answered
Communication delay & jitter delay modelling
Here is my interpretation of what you are asking. It seems that this woud be very easy in Simulink. You have signal PT which i...

5 days ago | 0

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Simulink switch that is based on probability
This seems to work for me (The uniform random number is set to a range of 0 to 1):

7 days ago | 0

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Rotating a coordinate with a rotation matrix
There seems to be some confusion regarding what the coordinate rotation transform is doing. One way to think about it is that i...

10 days ago | 0

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How can I position my textbox exact position in my plot?
Yes, this is possible to do, but it is complicated. When you place graphics in a figure window, they are located based on the f...

14 days ago | 0

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Call function by path or namespace?
One way to approach this is to create a separate folder (that is not on the Matlab path) for your project. When you set the Mat...

17 days ago | 0

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Difference between a vector and a bus signal
A bus signal is like a C++ structure. It can contain a variety of different signal types. A vector is an array, all elements a...

17 days ago | 0

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How to call .m file from an other .m file?
Use the command run(filename) Any variables defined in the script are available in the Matlab workspace.

17 days ago | 0

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How would you plot a graph which a ball then rolls down (say a y=x^2 graph)
Here is a model for the kinematics. clear data % I use data to save values in the time loop func = @(x) x.^2; % this is ...

22 days ago | 0

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Von Karman Wind Turbulence Model
V is the true airspeed. V is a scalar, and is used to calculate the scalar components of the turbulence field. The documentati...

24 days ago | 0

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How to find the angle between two quaternions?
I am more comfortable working with direction cosine matrices, so the way I would do this is to first convert the quaternions to ...

1 month ago | 1

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Eliminate algebraic loop without using memory block
Here is an interesting article on algebraic loops and memory blocks. (pertaining to continuous time models) https://blogs.math...

1 month ago | 0

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how to I add add a text in the Notes section (below the ppt slide)
on the VIEW tab, click on "notes page"

1 month ago | 0

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calculate difference of euler angles between two dynamic moving objects
You have two objects described in a common reference frame. Lets call the objects A and B, and the frame is the I frame. So if...

1 month ago | 1

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Is it possible to only rename instances of a variable that appear in the code after the point at which you edit the variable selected? (shift+enter)
I use a tool called UltraEdit. It has that capability. In the find/replace tab there is a checkbox for "replace all is from t...

1 month ago | 0

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program to find velocity of a UAV
This is a fun problem (aircraft design). I guess it's OK to give an answer on this, since it was homework 8 years ago! A quick...

1 month ago | 0

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how can i calculate the energy of the pixel in the image??
Here are a couple possible references https://www.mathworks.com/matlabcentral/answers/63441-to-find-energy-of-each-pixel-from-a...

2 months ago | 0

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simulink output size is not same as input size
The answer has to do with how you are saving variable "temp" from Simulink, but I cannot tell from the screenshot how this is be...

2 months ago | 0

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Eulers method range issue question
In your code, you specify: R=[1:16]; h=0.2; ic=4; Then you call the function [t,y]=myEuler(f,R,ic,h) Inside myEuler, it co...

2 months ago | 1

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How do you use Euler's Method to approximate the solution?
Euler's method approximates the area under a curve by using rectangular segments. The figure illustrates this process: You s...

2 months ago | 0

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Coorindate transforms to a satellite reference frame
In order to answer this question, we need a good definition of the coordinate frames involved. The only way to do this is to dr...

2 months ago | 0

Answered
How do I execute a function only one time in Simulink?
This is what rate transition blocks were created for. You might want to try this approach. Simply insert a rate transition blo...

2 months ago | 1

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How to substract one number from many numbers?
W = x - 0.6 Or, if you want to actualy subtract x from 0.6 it would be: W = -x + 0.6

2 months ago | 0

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How do I export a vector to workspace in simulink?
It'a actually very easy. Simulink has a block for combining two signals, called a "mux" block. Simply combine the two signals ...

3 months ago | 0

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thermodynamic properties of water in simulink
Sounds like a perfect application for using a table look-up. For a function of two variables, simulink has a "2-D Lookup Table...

3 months ago | 0

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Index exceeds the number of array elements (1)
In the calculation of xdot I see subscripted references for x (up to 12) and u (up to 4). You should check the size of x and u ...

3 months ago | 0

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Answered
how simulate PI ?
Yes, it's that easy. Did you try it? What are the results?

3 months ago | 1

Question


Is Walter Roberson a real person, or is he some kind of Matlab AI robot?
Just curious!

4 months ago | 8 answers | 13

8

answers

Answered
solve 4th order ode in simulink
Your diagram looks reasonable to me and it could work, but its hard to tell from a screen shot - especially when the block title...

4 months ago | 1

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