i am using these functionn blocks to write a program that will use Craemer's rule to compute matrix operation, however i figure the same things can be done in a more effective way , can anyone...

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Is this the shortest way of creating these functions
The program works well using these function blocks , but am sure the big guys wod do the same thing using less time and space. my program is to use Craemer's ruld to compute matric operation , can anyone assist please?

C#

const int MAX_SIZE = 20;//constructor with a max size of 20 sq matrix.

// Level 1 Functions
void print_message();
void initialize(float &, float *, float *, float *);
void allocate_floats(int &, float *&, float *&, float *&);
void initialize_dynamic_memory(float *, int);
void get_matrices(float [][MAX_SIZE], float *, int);
void calculate_variable_matrix(float &, float *, float *, float [][MAX_SIZE], float *, int);
void print_results(float *, float *, int, float);
void return_memory(float *, float *, float *);

// Level 2 Functions
void calculate_determinant(float &, float [][MAX_SIZE], int);
void calculate_modified_determinant(float *, float [][MAX_SIZE], float [], int);
void calculate_variables(float *, float *, float, int);
void print_determinants(float *, int, float);
void print_variables(float *, int, float);

// Level 3 Functions
void copy_matrix(float[][MAX_SIZE], float [][MAX_SIZE], int);
bool swap_rows(float [][MAX_SIZE], int, int);

Posted 27-Nov-11 4:09am

carlmack

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Richard MacCutchan 27-Nov-11 10:35am

All you have shown is a list of function declarations, from which it's impossible to guess anything.

carlmack 27-Nov-11 10:39am

hey guys hahah i am just learning the art, i am just looking how to use this new skillin my daily computation ,but a little flair would not hurt, haha
anyway could u look at my codes and give ma a feed back?
some aspects i took from my text and some from the net, but i knew what i wanted to do, so any assistance would be great.
thank you

Richard MacCutchan 27-Nov-11 10:45am

Did you actually bother to read my comment?

carlmack 27-Nov-11 10:54am

can i post my codes here

RaviRanjanKr 27-Nov-11 15:20pm

who stop you to post your codes. if you have problem you can post your effort to find out solution.

carlmack 27-Nov-11 11:05am

what do i do inorder to post myy entire code without violating the forum regulations?

Sergey Alexandrovich Kryukov 27-Nov-11 14:06pm

Nobody will ban you if you violate some regulations my mistake, but you want to post nicely just to avoid down-votes by irritated members and to get better chances to get valuable help.

Try to make code sample which can be posted all like one or more texts, as there is no a way to upload files. Create a sample, not all your existing code, make it minimalistic but complete (ideally, it should compile) and still demonstrate the problem. If the sample is too big, not many will volunteer to read it.

Alternatively, you can post your code on some other site (in ZIP or something like that) and post just the reference.

I would advise you pat attention to this: don't post any files which are parts of not source code: *.user, *.suo, *.dll, etc., don't repeat this typical mistake.

You need to indicate lines with errors, exceptions in your source code's comments.

Please use "Improve question". Please don't post non-solutions using "Submit your solutions" -- such posts will be removed, no one receives e-mail notification.
--SA

Addy Tas 27-Nov-11 11:12am

From what i see all i can say is that it does not seem like you are using classes to organize your code and/or group intermediate results. But hey; you give little to go by.

Stefan_Lang 28-Nov-11 8:34am

Just a little sidenote: you've defined a maximum size of 20x20, implying that your actual matrices might be smaller, but in the function parameter lists you are always using that maximum size, prohibiting any other size!

If you wish to use variable matrix sizes with standard C arrays, then the best way is to just define the matrix as a double pointer and pass the actual size as an additional parameter to the functions that need it. It would be easier though to use std::vector instead of C arrays.

Also, with matrices of that size, it's not a good idea to stick with single precision! Use double, not float. This is always a good idea when doing actual math with computers.

carlmack 28-Nov-11 14:49pm

oh totally appreciated Stefan_Lang, In the program i use a max size but this program itself allows for the use of smaller size. but i understand what u saying. I was trying to re-write the same code in c++ but using class instead of just function, however i thing i have a little difficulty in the public members and what private members would be, can u give an idea of how to approach it?

Stefan_Lang 29-Nov-11 3:58am

Well, I could answer your question, but you indicated you are just beginning, so a simple answer to a singular topic won't help you a lot - you'll just keep stumbling over things you don't understand and won't make any progress that way.

I strongly suggest you try yourself at one of the many C++ tutorials that can be found on the web. Here's a good start: http://www.cplusplus.com/doc/tutorial/

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-11-27T08:59:00

Cramer's rule is indeed very ineffective. In linear algebra used in application mathematics in computer algorithms, Gaussian Elimination is commonly used. Gaussian Elimination is way more effective. The benefit of Cramer's Rule it just the ease of use in manual calculations, not in computer algorithms. Computational complexity of directly applied Cramer's Rule is O(N⁴), while Gaussian Elimination is O(N³).

See:
http://en.wikipedia.org/wiki/Cramer%27s_rule[^],
http://en.wikipedia.org/wiki/Gaussian_elimination[^].

One widely used variation of Gauss method is Gauss–Jordan Elimination: http://en.wikipedia.org/wiki/Gauss-Jordan_elimination[^].

More exactly, in 2010 a new method of calculation based on Cramer's Rule was published. It was proven that the computational complexity of the new method is O(N³).

This is the reference:
Ken Habgood and Itamar Arel. 2010. Revisiting Cramer's rule for solving dense linear systems. In Proceedings of the 2010 Spring Simulation Multiconference (SpringSim '10).

Unfortunately, I'm not familiar with this work; and I don't have a Web reference, sorry.

[EDIT]

You can find some C++ or C implementation on the Web:
http://www.crbond.com/linear.htm[^],
http://icodesnip.com/snippet/cpp/gauss-jordan-elimination-dreamincode[^],
http://www.dreamincode.net/code/snippet1312.htm[^].

Google to find what suits you the best.

—SA