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# James Tursa

##### Last seen: Today
3 643 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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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(...

ungefär 2 timmar ago | 0

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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...

3 dagar ago | 0

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 ...

3 dagar ago | 0

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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...

4 dagar ago | 0

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 ...

8 dagar ago | 0

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...

8 dagar ago | 0

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

11 dagar ago | 0

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...

12 dagar ago | 0

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...

12 dagar ago | 0

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

12 dagar ago | 0

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' ...

12 dagar ago | 0

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...

12 dagar ago | 0

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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...

14 dagar ago | 0

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...

18 dagar ago | 0

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 ...

19 dagar ago | 0

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

19 dagar ago | 1

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...

26 dagar ago | 0

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

27 dagar ago | 1

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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 ...

27 dagar ago | 0

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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_...

28 dagar ago | 0

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The spacecraft free-fall math model

28 dagar ago | 0

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...

28 dagar ago | 0

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...

29 dagar ago | 0

How to fix error: "Index in position 1 is invalid. Array indices must be positive integers or logical values"
Type the following at the command line: dbstop if error Then run your code. When the error occurs, the code will pause with a...

ungefär en månad ago | 0

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Why do I get this error message "Array indices must be positive integers or logical values."
You forgot to multiply between the y and (y-1) Z = x(:).^2.*y.*(y-1).*(y+1); Also, make sure to use element-wise operators (wi...

ungefär en månad ago | 0

pointers in object-oriented matlab programing
MATLAB does not have variable pointers ... at least not in the sense of C/C++ like you are probably alluding to.

ungefär en månad ago | 0

Recursion in matrix calculation
This uses recursive calls (CalDet calls CalDet with smaller matrices until the size is 1x1). I.e., the recursion continues all ...

ungefär en månad ago | 1

How C++ gets struct values from Matlab
Looks like your strings are char type and not the newer string type. So you can try the following: mxArray *mx; char *name; ...

ungefär en månad ago | 0

Checking whether two complex matrices are equal
You can't rely on floating point calculations to give exact results. See this link: https://ch.mathworks.com/matlabcentral/ans...

ungefär en månad ago | 2

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