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

Answered

two body problem using ode45

I have studied the 2-body problem and the accuracy of different numerical solutions. See my comments in this thread: Discussi...

two body problem using ode45

I have studied the 2-body problem and the accuracy of different numerical solutions. See my comments in this thread: Discussi...

2 days ago | 1

Answered

All sample times for this block must be discrete. No continuous or constant sample times are allowed

On the Simulink toolbar, select "Display" - "Sample time" and check "all". This will show the sample time for all of the signa...

All sample times for this block must be discrete. No continuous or constant sample times are allowed

On the Simulink toolbar, select "Display" - "Sample time" and check "all". This will show the sample time for all of the signa...

2 days ago | 0

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...

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...

10 days ago | 0

Answered

Array indices must be positive integers or logical values

Matlab does not allow an index value of zero. deltaR = (b(0) ... similar in deltaS.

Array indices must be positive integers or logical values

Matlab does not allow an index value of zero. deltaR = (b(0) ... similar in deltaS.

13 days ago | 0

Answered

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,...

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,...

17 days ago | 0

Answered

Newton's Method error message

The variable x is not defined in w(n+1) = w(n) - (z(w(n))/dz(x(n)));

Newton's Method error message

The variable x is not defined in w(n+1) = w(n) - (z(w(n))/dz(x(n)));

20 days ago | 0

Answered

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...

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...

20 days ago | 0

Answered

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...

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...

27 days ago | 1

Answered

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

Simulink Transfer Function

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

Simulink Transfer Function

27 days ago | 0

Answered

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...

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...

28 days 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...

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...

28 days ago | 0

| accepted

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...

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...

30 days ago | 0

Answered

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 ...

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 ...

1 month ago | 0

| accepted

Answered

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...

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...

2 months ago | 0

Answered

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...

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...

2 months ago | 0

| accepted

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 months ago | 2 answers | 0

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...

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 months 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...

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 months ago | 0

Answered

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):

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 months ago | 0

| accepted

Answered

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...

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 months ago | 0

| accepted

Answered

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...

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...

3 months ago | 0

| accepted

Answered

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...

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...

3 months ago | 0

Answered

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...

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...

3 months ago | 0

Answered

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.

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.

3 months ago | 0

Answered

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 ...

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 months 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...

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 months 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 ...

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 months ago | 1

Answered

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...

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 months ago | 0

Answered

how to I add add a text in the Notes section (below the ppt slide)

on the VIEW tab, click on "notes page"

how to I add add a text in the Notes section (below the ppt slide)

on the VIEW tab, click on "notes page"

3 months ago | 0

Answered

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...

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 months ago | 1

| accepted