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Jim Riggs


Missile Defense Agency - Advanced Technology Group

197 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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Answered
Equation of Motion is Blowing Up
It's seems pretty clear from the plot of angle vs. speed that the system is gaining energy. You really need to draw a picture o...

6 jours ago | 0

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Array indices must be positive integers or logical values
Matlab does not allow an index value of zero. deltaR = (b(0) ... similar in deltaS.

9 jours ago | 0

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computation of GPS receiver position based on RINEX observation file
You are using the wrong function to try to read a file. The function 'read' operates on datastores, or images, or video frames,...

13 jours ago | 0

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Newton's Method error message
The variable x is not defined in w(n+1) = w(n) - (z(w(n))/dz(x(n)));

16 jours ago | 0

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Convert Milliseconds to Clock time from excel file
Let X be the time in miliseconds. Xs = X/1000; % the total time in seconds Hour = floor(Xs/3600) ; % The number of hours in x...

16 jours ago | 0

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How can I simulate data when I only know the derivative?
This is exactly how time-based simulations are done. You have the mathematical model of the system state derivative(s) (i.e. dx...

23 jours ago | 1

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how do I give in this kind of transfer function in Simulink
Simulink Transfer Function

23 jours ago | 0

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I can not find an error in the expression
It's hard to say without seeing how the variables r, t, and p are defined. If r and p are vectors of different length, then the...

24 jours ago | 2

Answered
create Simulink custom block
You can create almost anything you like. See the "user defined functions" tab in the library browser. You can use a "MATLAB fu...

24 jours ago | 0

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Answered
Matlab code for Euler method help
One thing that I notice is that you are defining N based on numel(T), but it looks like T is not yet defined, so what is the val...

26 jours ago | 0

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What is the best way to find angles between these two lines?
The angle between vectors is determined using the vector dot product. Calculate the unit vectors and angles as follows: v1x ...

environ un mois ago | 0

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Need technique to compare accuracy between different methods
As @darova suggests, if you have an analytical solution, then you can compare your numerical solution to the exact answer. This...

environ 2 mois ago | 0

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lookup table in simulink
There is no reason that non-uniform breakpoint spacing should be causing an error with the 1D interpolation function. I think t...

environ 2 mois ago | 0

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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...

2 mois ago | 2 answers | 0

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answers

Answered
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...

2 mois 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...

2 mois 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):

2 mois 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...

2 mois 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...

2 mois 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...

2 mois 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...

2 mois 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.

2 mois 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 ...

3 mois ago | 0

Answered
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...

3 mois ago | 0

Answered
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 ...

3 mois 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...

3 mois 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"

3 mois 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...

3 mois ago | 1

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Answered
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...

3 mois ago | 0

Answered
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...

3 mois ago | 0

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