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James Tursa


Last seen: 1 giorno ago
3.650 total contributions since 2007

Interested in external applications, mex & engine applications with Fortran, C, C++, etc, particularly in the areas of speed improvement and memory management efficiencies.

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Answered
How can I use a for loop to create new variables?
You might consider automatic array expansion. E.g., look at this result: t = 0:0.01:10; % row a = [0.1 1 3]'; % column y = e...

circa 17 ore ago | 1

Answered
Can someone convert this to matlab code?
So, you don't need any loops for this. Just use the automatic array expansion feature. E.g., take a look at what happens with ...

circa 17 ore ago | 0

Answered
Two variables need to be connected to one struct variable.
What about something like this: Results.First_Name = first_name{target}; Results.Last_Name = last_name{target}:

circa 18 ore ago | 0

| accepted

Answered
How would I write the function of f(x)=sin(x)*exp(-x/10)
The multiply. E.g., f = @(x) sin(x) .* exp(-x/10); You don't need it on the divide because you are dividing by a scalar.

circa 21 ore ago | 1

Answered
Error using ^ (line 51) Incorrect dimensions for raising a matrix to a power. Check that the matrix is square and the power is a scalar. To perform elementwise matrix powers, use '.^'.
This is often caused by using a matrix or vector in an equation when you thought you were using a scalar. E.g., take these lines...

1 giorno ago | 0

Answered
Reading 64 bit words
Try reading and keeping the type as uint64 (using the *) instead of converting to double: word = fread(fid,1,'*uint64');

1 giorno ago | 0

Answered
mex, error C3861: "mxGetDoubles": Cannot find the identifier, "mxGetUint8s": Cannot find the identifier ?
Those functions are for the R2018a memory model API. For that, you need to add the -R2018a option flag: mex myfile.cpp -R2018a...

1 giorno ago | 0

| accepted

Answered
Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.
You are missing an ending parenthesis, and also you probably need to use element-wise multiply: u3 = exp(-0.89*t) .* (1.75*cos(...

1 giorno ago | 0

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Answered
Solving a nonlinear ODE
Step 1: Solve your ODE for the highest order derivative, in this case Rdoubledot (on paper) Rdoubledot = stuff (you figure thi...

5 giorni ago | 0

Answered
Computational Complexity of matrix multiplication
This question is perhaps more involved than it looks on the surface, because by default MATLAB doesn't store the imaginary part ...

5 giorni ago | 0

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Answered
error:All functions in a script must be closed with an 'end'.( kindly see the code and help me to remove the error)
Looks like maybe this for iy = 1:H end for ix = 1:W should be just this for iy = 1:H for ix = 1:W Side Note: This would b...

6 giorni ago | 0

Answered
Using the euler method
p(ip) is the value of p at time t(ip). p isn't a function that you are passing time into like you are doing with p(t(ip)). So ...

10 giorni ago | 0

Answered
Finding Nonzero Elements in a Vector
You need to wrap this statement with an if-test and only execute it if v(CurrentPosition) is non-zero: prod = prod * v(CurrentP...

10 giorni ago | 0

Answered
Markov Chain probability steady state
Hint: The probability of moving from one state to another state in n steps is P^n

13 giorni ago | 0

Answered
Factorial without the Command
You could use either use a loop to multiply all of the numbers from 1 to n, or use recursion to multiply n by the factorial of n...

14 giorni ago | 0

Answered
Inputs a Vector and Returns the Second Smallest Element
Your algorithm always replaces Smallest and SecondSmallest at each iteration. Does that make sense? E.g., if the current Smalle...

14 giorni ago | 0

Answered
help w code error
You need to index S: f = -0.5 /(2.1+S(i));

14 giorni ago | 0

Answered
Hex to float like python struct.unpack()
Could be a Big Endian vs Little Endian thing. E.g., inserting a swapbytes( ) step: >> hex = 'C956F53D' hex = 'C956F53D' ...

14 giorni ago | 0

Answered
Python to MATLAB accuracy
Probably not. The trailing bits of floating point calculations in general can't be trusted. It you change the order of the calc...

14 giorni ago | 0

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Answered
solving coefficient with linear algebra
You basically have this: [ONES_COLUMN, X_COLUMN, Y_COLUMN] * p = DATA You know all the CAPS stuff. So just use the standard l...

16 giorni ago | 0

Answered
Composite Functions with a function with two ranges
For example, take the first one: (g o f)(x) This is just g(f(x)) which is g(x^2) Assuming we are talking only about real in...

20 giorni ago | 0

Answered
im trying to create a while loop for random numbers and it says if its even or odd
Change this while times < 20 to this while Ecounter < 20 and change this Ecounter = 0+1; to this ...

21 giorni ago | 0

Answered
The Body Mass Index, or BMI
Just get rid of these lines: function BMI=findbmi(Weight,Height)

21 giorni ago | 1

Answered
From where is this exp in syms calculus?
The solution space has multiple values, not just one. The solver has parameterized the solution space for you. There are multi...

28 giorni ago | 0

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Answered
simulate a dice throw
doc randi E.g., for a single throw you could use randi(6)

29 giorni ago | 1

| accepted

Answered
Why do I get "Array indices must be positive integers or logical values" error when using?
k is 3.5 So y(k-1) is y(2.5) and y(k-2) is y(1.5). The indexes are not positive integers, hence the error. Maybe you meant ...

29 giorni ago | 0

| accepted

Answered
How to fill mxArray with mxGetComplexDoubles?
No, this would not be expected to work. In the first place, you need to use mxDOUBLE_CLASS to create the mxArray, not mxSINGLE_...

30 giorni ago | 0

| accepted

Answered
The spacecraft free-fall math model
See this link for an example of the parachute problem: https://www.mathworks.com/matlabcentral/answers/516385-code-not-working-...

30 giorni ago | 0

Answered
Satellite Orbit, Friction Acceleration Function
See this link for an example that uses atmospheric drag with a satellite (in this case a satellite falling to Earth): https://w...

30 giorni ago | 0

Answered
Fibonacci Series Using Recursive Function
All of your recursive calls decrement n-1. Eventually you will wind up with the input n=0 and just return v=0, which is not wha...

circa un mese ago | 0

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