I once had a matrix working like this
matrix[20][2]
So, since its indexed with 0, I used them as matrix[i][0] or matrix[i][1].
Then the other day, I forgot the 0 index, and used matrix[i][2].
And it worked perfectly fine! And worse so, the program didn't work anymore when I revert that back to matrix[i][1]. Also matrix[i][0] now had ridiculous values inside.
More importantly, there are other places in the code in which the matrix works with matrix[i][0 or 1]. THE SAME MATRIX.
Its just this particular segment that has gone haywire.
I am using mingw latest version, and no the matrices are not passed by reference to anything or anywhere. And they are all initialized to all 0 values by a loop at the start of the code. The matrices are double type.
My program is working fine, after about half an hour of randomly placing 0s, 1s and 2s somehow its working very fine. But I am afraid it would go bonkers again on another machine.
Does anyone know whats happening? Is it my compiler or my coding?
Thanks!
1 1442
All the indexes do is perform a pointer arithmetic calculation. If the indexes are inside your array you get good results. If they aren't, you get bad results since you have corrupted memory outside the array bounds.
Read this article: http://bytes.com/forum/thread772412.html.
Post again of your still have questions.
Sign in to post your reply or Sign up for a free account.
Similar topics |
by: Jason |
last post by:
Hello. I am trying to learn how operator overloading works so I wrote
a simple class to help me practice. I understand the basic opertoar
overload like + - / *, but when I try to overload more complex
operator, I get stuck.
Here's a brief description what I want to do. I want to simulate a
matrix (2D array) from a 1D array. so what I have so far is something
like this:
class Matrix
|
by: christopher diggins |
last post by:
Here is some code I wrote for Matrix multiplication for arbitrary
dimensionality known at compile-time. I am curious how practical it is. For
instance, is it common to know the dimensionality of matricies at
compile-time? Any help would be appreciated. Hopefully this code comes in
useful for someone, let me know if you find it useful, or if you have
suggestions on how to improve it.
// Public Domain by Christopher Diggins, 2005
...
|
by: Martin Jørgensen |
last post by:
Hi,
I've made a program from numerical recipes. Looks like I'm not allowed
to distribute the source code from numerical recipes but it shouldn't
even be necessary to do that.
My problem is that I'm not very experienced with pointers, pointers to
pointers and the like and I got 4 compiler warnings + I don't completely
understand how to build this "compact matrix" (see later).
|
by: Frank-O |
last post by:
Hi ,
Recently I have been commited to the task of "translating" some complex
statistical algorithms from Matlab to C++. The goal is to be three
times as fast as matlab ( the latest) .
I've used various techniques ( loop unrolling, loop jamming...) and
tried some matrix libraries : newmat (slow for large matrix) , STL
(fast but ..not usefull) , hand coding (brain consuming...), and
recently Meschach...
|
by: jjiyunlee |
last post by:
Hi,
I'm new to C (and programming in general), and I have to say that this site has helped me learn a great deal about C (thanks everybody!!). I've looked through several discussions specifically about reading a matrix from a file, but I think (based on my admittedly small amount of knowledge about things like this) that my problem is slightly different. My for-loops for fscanf-ing values from a user-specified file seems to be ignored...
| |
by: DarrenWeber |
last post by:
Below is a module (matrix.py) with a class to implement some basic
matrix operations on a 2D list. Some things puzzle me about the best
way to do this (please don't refer to scipy, numpy and numeric because
this is a personal programming exercise for me in creating an
operational class in pure python for some *basic* matrix operations).
1. Please take a look at the __init__ function and comment on the
initialization of the list data...
|
by: adam.kleinbaum |
last post by:
Hi there,
I'm a novice C programmer working with a series of large (30,000 x
30,000) sparse matrices on a Linux system using the GCC compiler. To
represent and store these matrices, I'd like to implement the sparse
matrices as a doubly-linked list, in which each non-zero cell is
stored roughly as follows:
int rownum
int colnum
|
by: Anolethron |
last post by:
Wrong one:
void minptr (int *matrix, int rows, int columns,int *min){
int i=0,j=0;
*min=*matrix; //!!!!!!!!!!!!!!!!!
for (i=0; i < rows; i++) {
for (j=0; j < columns; j++) {
if( *min *(matrix+(i*columns)+j) ) {
min = (matrix+(i*columns)+j);
|
by: lovecreatesbea... |
last post by:
Hello experts,
I code an function to rotate a matrix by 90 degrees clockwise. The
matrix can be in any size provided its length equals to width. The one
minor limitation is that this requires an extra external macro
definition MTXROT_SIZE. Your comments are welcome on this code. Thank
you for your time.
/
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look !
Part I. Meaning of...
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
| |
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
|
by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth.
The Art of Business Website Design
Your website is...
|
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
|
by: tracyyun |
last post by:
Dear forum friends,
With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
|
by: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert into image.
Globals.ThisAddIn.Application.ActiveDocument.Select();...
| |
by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
| |