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Full Discussion: does any one know how to solve?
Top Forums Programming does any one know how to solve? Post 302229272 by redoubtable on Tuesday 26th of August 2008 03:32:53 PM
Old 08-26-2008
I think we're failing to communicate due to my poor English.

Quote:
Originally Posted by shamrock
On the contrary if performance really matters one would go with a dynamic solution in order to minimize the overhead of allocating a very large memory segment and using only a small portion of it. A static solution is not optimized in terms of memory management.
This is a question of circumstance, memory access speed is generally the same for both static and dynamic memory but if you're creating a program where (malloc()ing) and free()ing entries happens too often a static implementation (with proper algorithms to avoid overflows) should be prefered.


Quote:
Why would you need to expand a static array. Don't you think that's an oxymoron? If you need to expand an array it becomes dynamic by default. The only case where that solution won't work is the gray scenario you suggested where the number of allocated entries is more than the used ones; as in the case below where the array has 10 entries allocated and only 5 are used. Smilie
I was not referring about expanding the array itself! I was talking about expanding the number of entries inside the array (so called "gray scenario"). The gray situation has some indications. For instance, if the proper algorithm (avoid bound overflows) is used and we're going to add and remove many entries at a time (for example, buffer purposes).

Quote:
You won't need double level of indirection...the memory returned by malloc() will be assigned to a pointer to an object of type struct empRec that is a single level of indirection. My earlier post showed that scenario.
Yes I never said it was imperative I just said that you where proposing a one-level solution when the user was having a two-leveled problem. I just said that pointer you refer would have to be linked inside a list (linked lists) to fulfill the user's problem or be inside a double level pointer.


IMHO the best solution is not generally applied to every case hence there is no point saying "dynamic is the best way" or "static is the best way". The best solution is that which fits the requirements and has best performance.
 

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LEARN ABOUT DEBIAN

ctrsyl

ctrsyl.f(3)							      LAPACK							       ctrsyl.f(3)

NAME

       ctrsyl.f -

SYNOPSIS

   Functions/Subroutines
       subroutine ctrsyl (TRANA, TRANB, ISGN, M, N, A, LDA, B, LDB, C, LDC, SCALE, INFO)
	   CTRSYL

Function/Subroutine Documentation
   subroutine ctrsyl (characterTRANA, characterTRANB, integerISGN, integerM, integerN, complex, dimension( lda, * )A, integerLDA, complex,
       dimension( ldb, * )B, integerLDB, complex, dimension( ldc, * )C, integerLDC, realSCALE, integerINFO)
       CTRSYL

       Purpose:

	    CTRSYL solves the complex Sylvester matrix equation:

	       op(A)*X + X*op(B) = scale*C or
	       op(A)*X - X*op(B) = scale*C,

	    where op(A) = A or A**H, and A and B are both upper triangular. A is
	    M-by-M and B is N-by-N; the right hand side C and the solution X are
	    M-by-N; and scale is an output scale factor, set <= 1 to avoid
	    overflow in X.

       Parameters:
	   TRANA

		     TRANA is CHARACTER*1
		     Specifies the option op(A):
		     = 'N': op(A) = A	 (No transpose)
		     = 'C': op(A) = A**H (Conjugate transpose)

	   TRANB

		     TRANB is CHARACTER*1
		     Specifies the option op(B):
		     = 'N': op(B) = B	 (No transpose)
		     = 'C': op(B) = B**H (Conjugate transpose)

	   ISGN

		     ISGN is INTEGER
		     Specifies the sign in the equation:
		     = +1: solve op(A)*X + X*op(B) = scale*C
		     = -1: solve op(A)*X - X*op(B) = scale*C

	   M

		     M is INTEGER
		     The order of the matrix A, and the number of rows in the
		     matrices X and C. M >= 0.

	   N

		     N is INTEGER
		     The order of the matrix B, and the number of columns in the
		     matrices X and C. N >= 0.

	   A

		     A is COMPLEX array, dimension (LDA,M)
		     The upper triangular matrix A.

	   LDA

		     LDA is INTEGER
		     The leading dimension of the array A. LDA >= max(1,M).

	   B

		     B is COMPLEX array, dimension (LDB,N)
		     The upper triangular matrix B.

	   LDB

		     LDB is INTEGER
		     The leading dimension of the array B. LDB >= max(1,N).

	   C

		     C is COMPLEX array, dimension (LDC,N)
		     On entry, the M-by-N right hand side matrix C.
		     On exit, C is overwritten by the solution matrix X.

	   LDC

		     LDC is INTEGER
		     The leading dimension of the array C. LDC >= max(1,M)

	   SCALE

		     SCALE is REAL
		     The scale factor, scale, set <= 1 to avoid overflow in X.

	   INFO

		     INFO is INTEGER
		     = 0: successful exit
		     < 0: if INFO = -i, the i-th argument had an illegal value
		     = 1: A and B have common or very close eigenvalues; perturbed
			  values were used to solve the equation (but the matrices
			  A and B are unchanged).

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Definition at line 157 of file ctrsyl.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.1							  Sun May 26 2013						       ctrsyl.f(3)
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