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James Tursa


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3.372 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
Binary Image: Count number of pixels that are 1.
nnz(bw)

ongeveer 8 uur ago | 1

Answered
error when running a function
Do not push the green triangle "go" button in the editor since that calls the function without any input arguments. Instead, cal...

ongeveer 11 uur ago | 0

Answered
solving a set of differential equations with ode45
Initial conditions is a 4-element vector: IC1=[0; 0; 298; 298]; But in your derivative function you have this: M=[5,15,25,55]...

ongeveer 16 uur ago | 0

| accepted

Answered
Loops - physics - nonlinear gravity & acceleration
Your immediate problem is that h is a vector, so the right hand side of this statement is a vector: g(i+1)=(400000000/(6371+h...

ongeveer 16 uur ago | 0

Answered
Looping over column and returning values where conditions are met
In general, perform find( ) on the condition you want. E.g., find(matrix(:,4)>80) would return the row numbers where the 4th c...

1 dag ago | 0

Answered
sparse half-precision matrices
The sparse format in MATLAB only supports double and logical data types. To use any other data type you would have to write all...

1 dag ago | 0

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Answered
RK4/AB4, need help with correct code for 2 second order equations in Matlab
So, first define a 4-element state vector. To keep the nomenclature the same as the MATLAB docs, I will use the variable name y....

1 dag ago | 0

Answered
Cell Arrays and Indexing?
This is the reverse of your last assignment. It needs only one loop over the number of rows, and the cell array element for tha...

2 dagen ago | 0

| accepted

Answered
Cell arrays and Indexing with Cells HELP?
This row = Q(1:end); col = Q{1:end}; Z(row, col) = true; is actually a good attempt and shows you understand the problem .....

2 dagen ago | 0

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Answered
repeat the iteration with an error using try/catch
Maybe this construct does what you want while( true ) try MyProgramHere ...

2 dagen ago | 0

Answered
Storing doubles in the smallest integer class for which they fit without changing their value?
Some hints: Don't use loops, use vectorized code to figure out which integer size works. intmax(type) gives you the largest va...

3 dagen ago | 0

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Answered
How do I make a function work with vectors?
Use element-wise divide operator ./ (with the dot) instead of the matrix divide operator / (without the dot). E.g., tanH(x)=((...

3 dagen ago | 0

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Answered
Question already answered - ODE solving use RK4
Your basic problem is that you have two states, x and y, but your function arguments are inconsistent with this. Take this code:...

3 dagen ago | 1

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Answered
Really! fprintf cell error
What happens if you change this fprintf(fid, '%d %s %s %f',shape{i,:}); to this fprintf(fid, '%d %s %s %f',shape{i,1},shape{i...

3 dagen ago | 0

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Answered
MATLAB Homework Problem: "Incorrect use of '=' operator" in a for loop
This: for (i = 2:0.5:15 && j = -2:0.5:12) Needs to be two nested loops: for i = 2:0.5:15 for j = -2:0.5:12

3 dagen ago | 1

Answered
Homework help.(User defined functions )
Hint: See these functions: doc size doc isequal doc error

3 dagen ago | 0

| accepted

Answered
trouble understanding for loops
The first problem is getting the input from the user. This assigns a char string to pv: pv=('What was your original mortgage v...

4 dagen ago | 0

Answered
OR statement in a while Loop
Change to AND: while ((playerhp > 0) && (enemyhp > 0)) I.e., you only do the while loop when both hp are positive. It eit...

4 dagen ago | 0

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Answered
Fastest way to find the row number containing the most amount of black pixels in a gray-scale image?
[~,row_blackPix] = max(sum(image <= 20,2))

4 dagen ago | 0

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Answered
Varying step size for RK Method?
The only variable that depends on a new n is h, so only recalculate h and then run your loop as is. Although if you want to make...

4 dagen ago | 0

Answered
conversion from base 13 to IEEE 754
For the base 13 conversions: doc dec2base doc base2dec https://www.mathworks.com/help/matlab/ref/dec2base.html https://www.m...

5 dagen ago | 0

Answered
Whats wrong with my code? Taylor series Approx with error
You probably just need an absolute value error = abs((true-s)/true)*100; %Percent Error Formula That being said, true and erro...

5 dagen ago | 0

Answered
Functions and For Loops For Polynomials
Some guidance: 1) The sum=0 part needs to be moved outside the loop, prior to the loop starting. The way you have it the sum re...

5 dagen ago | 1

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Answered
How can I randomly select a subset of logicals?
T = your logical trials vector n = 20; % number of trials to keep f = find(T); % find the location of the 1's f = f(randperm(...

6 dagen ago | 1

| accepted

Answered
Custom help information on structure fields
See this discussion: https://www.mathworks.com/matlabcentral/answers/480829-what-is-the-best-way-to-insure-that-all-of-my-funct...

6 dagen ago | 2

| accepted

Answered
Error using * Matrix dimensions must agree.
Change this piv=A(i:i); to this piv=A(i,i); And change this fac=A(j:i)./piv; to this fac=A(j,i)./piv;

6 dagen ago | 0

Answered
how to print multiple variables with strings in between ?
You could use fprintf. E.g. >> a = 5; >> b = 7; >> fprintf("Variable a equals: %g\n",a); Variable a equals: 5 >> fprintf("V...

6 dagen ago | 1

| accepted

Answered
Swapping last matrix columns
From your description, I don't see how your code works for anything other that inputs having two columns. I would guess that thi...

6 dagen ago | 0

Answered
C/Fortran callback to MATLAB
Maybe this can give you the framework you need. I have made some assumptions about how things are connected. You pass in a cha...

6 dagen ago | 0

| accepted

Answered
Common numbers between arrays
You could write some code using the intersect( ) function for this. E.g., the first result >> A = {[1,2,3], [3 4 5 6], [3 7 8 ...

6 dagen ago | 1

| accepted

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