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James Tursa


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3,657 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
Wrapper to run 32-Bit mex files on 64-Bit MATLAB
32-bit mex files are not standalone code. They interact with 32-bit MATLAB library code which interacts with the 32-bit MATLAB ...

1 hour ago | 0

Answered
Taylor series for sin(x) doesn't give the right answer above 34 radians
The larger x is, the more cancellation error you are going to get with the intermediate sums. It would be best to reduce the ra...

13 hours ago | 0

Answered
code for eulers method help
This needs to be outside of and prior to your loop, and r needs a multiply operator: f=@(y)r*(1-(y/L))*y-((p*y^2)/(q+y^2)); Th...

21 hours ago | 1

Answered
minutes to hour and minutes
Make mins a column vector, or use mins(:) in your function handle.

1 day ago | 0

Answered
syntax error using complex loops
Did you mean while c <= 19 For loops should be looping over a fixed number of iterations, not a logical condition. While loop...

2 days ago | 0

Answered
Create Array that reorders given values to have smallest first and largest last while maintaining the rest of the array.
That 2nd loop needs to run in reverse order. You need to bubble that smallest number which might be near the back all the way t...

2 days ago | 0

Answered
Need helping creating and solving for this equation: f(t)=4- t^2 e^(-3t)
Here is a basic outline to get you started: n = 100; % Number of elements t = zeros( you fill this in ); % create an t vector ...

4 days ago | 0

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...

7 days 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 ...

7 days 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}:

7 days ago | 0

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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.

7 days 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...

7 days ago | 0

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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');

7 days ago | 0

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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...

8 days ago | 0

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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(...

8 days 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...

11 days 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 ...

11 days 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...

12 days 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 ...

16 days 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...

16 days 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

19 days 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...

20 days 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...

20 days ago | 0

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

20 days 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' ...

20 days 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...

20 days 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...

22 days 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...

26 days 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 ...

27 days ago | 0

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

27 days ago | 1

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