James Tursa
2 855 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.
James Tursa's Badges
Contribute at least one answer each month for 36 consecutive months
Awarded to James Tursa on 20 Jul 2017
Accept 5 answers given by other contributors
Awarded to James Tursa on 20 Jul 2017
Answer 3 questions that were unanswered for more than 30 days
Awarded to James Tursa on 20 Jul 2017
100 of your answers have been accepted
Awarded to James Tursa on 20 Jul 2017
Provide your first answer ever to someone else's question
Awarded to James Tursa on 20 Jul 2017
Solve a problem for the first time
Awarded to James Tursa on 26 Feb 2012
How to correct "Parse" error
Don't have your function at the top of this. Put it at the end or in a separate file. E.g., t = 1; while (height ~=0) h =...
4 dagar ago | 0
I have a matrix (57,3600,45), how can I create matrices with (3600,45)?
Is this what you want? k = some integer index squeeze(your_matrix(k,:,:))
4 dagar ago | 0
Square root table without using arrays
You need to put the new line \n in appropriate places in your loops. In particular, you only need one new line \n printed once y...
4 dagar ago | 0
| accepted
Memory Size and Processor Speed
Yes you can run MATLAB on this. What tasks will you typically be using MATLAB for?
6 dagar ago | 0
| accepted
How to? - Complex numbers
E.g., for an anonymous function you need to give the input argument list first. E.g., for a generic derivative function that tak...
8 dagar ago | 0
And/or between two 3d arrays
Do you mean this? sum(array1>250 & array2>170,3);
8 dagar ago | 0
Function in Fortran to Funciton in Matlab
function result = F0(n,x) if( n<2 ) error('bad argument n in F0') end tox=2.0/x; bkm=F00(x); bk=F01(x); for j=1:n-1 ...
11 dagar ago | 1
| accepted
differentiating function & getting different answer
Perhaps you are shadowing the MATLAB function diff with a function of your own. Make sure diff is pointing to the MATLAB functio...
12 dagar ago | 0
Invalid Syntax at '='.Possibly,a ),} or ] is missing at line 6 .
The { } formulation for blocking code is not valid MATLAB syntax. To fix this: Get rid of the open brace { Replace the close b...
13 dagar ago | 1
| accepted
use this vector and a mathematical expression to create the following vectors:
Yes. It works for me: >> x= [1, 2, 3, 4 ,5] x = 1 2 3 4 5 >> x1= x.*[1,128,243,64,5] x1 = 1 25...
18 dagar ago | 0
Extracting matrix values for an algorithm
Something like this? xy = your n x 2 array n = size(xy,1); for k=1:n % run your algorithm here with x = xy(k,1) and y = ...
18 dagar ago | 1
| accepted
Basic power rule ((a^b)^c = a^(b*c)) does not work
This has been discussed in this forum before. Raising complex numbers to a power is a multi-valued operation. MATLAB picks one...
18 dagar ago | 1
Is it possible to use logical indexing to specify between a number interval and include a value outside that interval.
E.g., Mask = ismember(str,[' ','a':'z','A':'Z']); Or using your method Mask = (65<=Ustr & Ustr<=90) | Ustr == 32;
19 dagar ago | 1
| accepted
BEGINNER PROBLEM: Trying to finish up an assignment but I am stuck with this error and am not sure how to fix
lab_total and assign_total and exam_total are all vectors, so the right hand side expression is a vector. You try to stuff that...
20 dagar ago | 1
I have a problem with this ode45
I don't see anywhere in your code where you define i and j before using them as indexes into Phi0 and Z0, so they default to the...
20 dagar ago | 0
Vector matrix multiplication with a condition
For later versions of MATLAB: c = all(A==B | A==2,2); For earlier versions: c = all(bsxfun(@eq,A,B) | A==2,2);
20 dagar ago | 0
| accepted
Can ode45 solve a ODE with space dependent parameters?
Yes. In general, if the derivative is a function of current state and time (even if there are vectors or matrices involved), the...
21 dagar ago | 2
| accepted
Is it possible to set rules for calculating permutations of column vectors?
Use the diff( ) function to calculate all of the permutations, and then count the number of valid ones. E.g., P = perms(1:i...
22 dagar ago | 1
| accepted
Get UNIX standard timestamp on MATLAB
You need to be careful about how you use the posixtime(t) function. From the documentation: "...If the time zone of t is not sp...
ungefär en månad ago | 2
How can I determine the angle between two vectors in MATLAB?
This topic has been discussed many times on the Newsgroup forum ... if I looked hard enough I'm sure I could find several Roger ...
ungefär 2 månader ago | 3
"To RESHAPE the number of elements must not change".This error occurs in line18.how to correct this error?
This expression is only going to work if size(a,1)*size(a,1) = numel(a): reshape(a,size(a,1),size(a,1),1); What are you trying...
ungefär 2 månader ago | 0
Matlab crashes but Octave doesn't
What happens if you do the A\b differently? E.g., doing the LU decomposition manually and then backsolving yourself? Or doing pi...
ungefär 2 månader ago | 0
| accepted
R2018b real times complex multiplication
Probably related to the fact that complex variables changed to an interleaved storage format in R2018a. So my guess is this is w...
ungefär 2 månader ago | 2
| accepted
Write a function called WordProduct to calculate the alphabetic word product of a character vector.
Hints to get you started: Look at the upper( ) and lower( ) functions What happens if you subract 'a' or 'A' from your vector?...
ungefär 2 månader ago | 0
Changing elements with a condition
clear X2 X3 [m,n] = size(X1); X2(2:m,2:n) = X1(1:m-1,1:n-1); X3(3:m,3:n) = X1(1:m-2,1:n-2);
ungefär 2 månader ago | 1
| accepted
I dont understand the vectors and element parts.
Typo. This j*y*(1) <-- Uses the full vector y times the scalar 1 should be this j*y(1) <-- Uses only the y(1) element
2 månader ago | 0
| accepted
Efficient indexing with nested object and object arrays
Whether this works or not depends on what is in the properties, but have you tried simple concatenation on the rhs? [out] = [pa...
2 månader ago | 0
Matlab not squaring imaginary part of complex number.
Squaring complex numbers does not in general result in real numbers. It all depends on the phase angles involved (would need to ...
2 månader ago | 0
find roots of determinant
Since the determinant of a matrix is equal to the product of its eigenvalues, maybe you could work with eig(A(x)) instead and tr...
2 månader ago | 0
Rotation Matrix with euler angles
The best I can guess is you are given three Euler angles with a sigma for noise, and you want to output a corresponding rotation...
2 månader ago | 0
| accepted