nota bene. This answer has 20 upvotes now, but it is not intended as an endorsement of std::valarray. In my experience, time is better spent installing and learning to use a full-fledged math library such as Eigen. Valarray has fewer features than the competition, but it isn’t more efficient or particularly easier to use. If … Read more
It actually is possible to do what you want, but you have to use the functional form of the indexing operator. When you perform an indexing operation using (), you are actually making a call to the subsref function. So, even though you can’t do this: value = magic(5)(3, 3); You can do this: value … Read more
To “reverse pivot”, “unpivot” or “flatten”: For Excel 2003: Activate any cell in your summary table and choose Data – PivotTable and PivotChart Report: For later versions access the Wizard with Alt+D, P. For Excel for Mac 2011, it’s ⌘+Alt+P (See here). Select Multiple consolidation ranges and click Next. In “Step 2a of 3”, choose … Read more
So the question really is Understanding 4×4 homogenous transform matrices well without the math behind the only thing that left is geometric representation/meaning which is far better for human abstraction/understanding. So what the 4×4 matrix is? It is representation of some Cartesian coordinate system and it is composed of: 3 basis vectors (one for each … Read more
Most likely no difference at all. The compiler will inline the function just as much as it inlines the macro. Since macros are much harder to use in a debugger, use a function. And as I always say in case of “which performs better”, you should always benchmark the different options, since differences in compilers … Read more
So, as much as it is fast and convenient to put code into a header, it almost always leads to compile errors that take longer to track down than the time it takes to create the standard .h and .cpp files, especially with this much code. I’m not exactly sure where the problem was, but … Read more
If you don’t know the external indice, you’d have to loop through every element in the array and compare the values of their x/y coordinates to your given coordinates, then return the ID when you find a match, or some sentinel value if you reach the end without finding a match.
There is really nothing you can do. If matrix don’t satisfy conditions of some method, use other methods that can be applied to this matrix. Remember, in such bad cases you can use Gauss Elimination to solve SLAE.
The alpha method returns an array that is sorted in reverse way, while the omega method directly reverses the array passed in parameter. Hence alpha(matrix[0]); does nothing you can see while omega(matrix[1]); changes the order of the second row of your matrix. As Shree Krishna said, you can find it by debugging.
#include <stdio.h> #include <stdlib.h> #include <time.h> #include <string.h> void bubble_sort(void *base, size_t n, size_t size, int (*cmp)(const void*, const void *)); int cmp_int(const void *a, const void *b){ int x = *(const int *)a; int y = *(const int *)b; return x < y ? -1 : x > y; } int main() { int … Read more