ilaenv.c

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/*
* ======================================================================
* NIST Guide to Available Math Software.
* Fullsource for module SSYEVX.C from package CLAPACK.
* Retrieved from NETLIB on Fri Mar 10 14:23:44 2000.
* ======================================================================
*/
#include <f2c.h>

integer ilaenv_(integer *ispec, char *name, char *opts, integer *n1, integer *
	n2, integer *n3, integer *n4, ftnlen name_len, ftnlen opts_len)
{
/*  -- LAPACK auxiliary routine (version 2.0) --   
       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
       Courant Institute, Argonne National Lab, and Rice University   
       September 30, 1994   


    Purpose   
    =======   

    ILAENV is called from the LAPACK routines to choose problem-dependent 
  
    parameters for the local environment.  See ISPEC for a description of 
  
    the parameters.   

    This version provides a set of parameters which should give good,   
    but not optimal, performance on many of the currently available   
    computers.  Users are encouraged to modify this subroutine to set   
    the tuning parameters for their particular machine using the option   
    and problem size information in the arguments.   

    This routine will not function correctly if it is converted to all   
    lower case.  Converting it to all upper case is allowed.   

    Arguments   
    =========   

    ISPEC   (input) INTEGER   
            Specifies the parameter to be returned as the value of   
            ILAENV.   
            = 1: the optimal blocksize; if this value is 1, an unblocked 
  
                 algorithm will give the best performance.   
            = 2: the minimum block size for which the block routine   
                 should be used; if the usable block size is less than   
                 this value, an unblocked routine should be used.   
            = 3: the crossover point (in a block routine, for N less   
                 than this value, an unblocked routine should be used)   
            = 4: the number of shifts, used in the nonsymmetric   
                 eigenvalue routines   
            = 5: the minimum column dimension for blocking to be used;   
                 rectangular blocks must have dimension at least k by m, 
  
                 where k is given by ILAENV(2,...) and m by ILAENV(5,...) 
  
            = 6: the crossover point for the SVD (when reducing an m by n 
  
                 matrix to bidiagonal form, if max(m,n)/min(m,n) exceeds 
  
                 this value, a QR factorization is used first to reduce   
                 the matrix to a triangular form.)   
            = 7: the number of processors   
            = 8: the crossover point for the multishift QR and QZ methods 
  
                 for nonsymmetric eigenvalue problems.   

    NAME    (input) CHARACTER*(*)   
            The name of the calling subroutine, in either upper case or   
            lower case.   

    OPTS    (input) CHARACTER*(*)   
            The character options to the subroutine NAME, concatenated   
            into a single character string.  For example, UPLO = 'U',   
            TRANS = 'T', and DIAG = 'N' for a triangular routine would   
            be specified as OPTS = 'UTN'.   

    N1      (input) INTEGER   
    N2      (input) INTEGER   
    N3      (input) INTEGER   
    N4      (input) INTEGER   
            Problem dimensions for the subroutine NAME; these may not all 
  
            be required.   

   (ILAENV) (output) INTEGER   
            >= 0: the value of the parameter specified by ISPEC   
            < 0:  if ILAENV = -k, the k-th argument had an illegal value. 
  

    Further Details   
    ===============   

    The following conventions have been used when calling ILAENV from the 
  
    LAPACK routines:   
    1)  OPTS is a concatenation of all of the character options to   
        subroutine NAME, in the same order that they appear in the   
        argument list for NAME, even if they are not used in determining 
  
        the value of the parameter specified by ISPEC.   
    2)  The problem dimensions N1, N2, N3, N4 are specified in the order 
  
        that they appear in the argument list for NAME.  N1 is used   
        first, N2 second, and so on, and unused problem dimensions are   
        passed a value of -1.   
    3)  The parameter value returned by ILAENV is checked for validity in 
  
        the calling subroutine.  For example, ILAENV is used to retrieve 
  
        the optimal blocksize for STRTRI as follows:   

        NB = ILAENV( 1, 'STRTRI', UPLO // DIAG, N, -1, -1, -1 )   
        IF( NB.LE.1 ) NB = MAX( 1, N )   

    ===================================================================== 
*/
/* >>Start of File<<   
       System generated locals */
    integer ret_val;
    /* Builtin functions   
       Subroutine */ int s_copy(char *, char *, ftnlen, ftnlen);
    integer s_cmp(char *, char *, ftnlen, ftnlen);
    /* Local variables */
    static integer i;
    static logical cname, sname;
    static integer nbmin;
    static char c1[1], c2[2], c3[3], c4[2];
    static integer ic, nb, iz, nx;
    static char subnam[6];



    switch (*ispec) {
	case 1:  goto L100;
	case 2:  goto L100;
	case 3:  goto L100;
	case 4:  goto L400;
	case 5:  goto L500;
	case 6:  goto L600;
	case 7:  goto L700;
	case 8:  goto L800;
    }

/*     Invalid value for ISPEC */

    ret_val = -1;
    return ret_val;

L100:

/*     Convert NAME to upper case if the first character is lower case. */

    ret_val = 1;
    s_copy(subnam, name, 6L, name_len);
    ic = *(unsigned char *)subnam;
    iz = 'Z';
    if (iz == 90 || iz == 122) {

/*        ASCII character set */

	if (ic >= 97 && ic <= 122) {
	    *(unsigned char *)subnam = (char) (ic - 32);
	    for (i = 2; i <= 6; ++i) {
		ic = *(unsigned char *)&subnam[i - 1];
		if (ic >= 97 && ic <= 122) {
		    *(unsigned char *)&subnam[i - 1] = (char) (ic - 32);
		}
/* L10: */
	    }
	}

    } else if (iz == 233 || iz == 169) {

/*        EBCDIC character set */

	if (ic >= 129 && ic <= 137 || ic >= 145 && ic <= 153 || ic >= 162 && 
		ic <= 169) {
	    *(unsigned char *)subnam = (char) (ic + 64);
	    for (i = 2; i <= 6; ++i) {
		ic = *(unsigned char *)&subnam[i - 1];
		if (ic >= 129 && ic <= 137 || ic >= 145 && ic <= 153 || ic >= 
			162 && ic <= 169) {
		    *(unsigned char *)&subnam[i - 1] = (char) (ic + 64);
		}
/* L20: */
	    }
	}

    } else if (iz == 218 || iz == 250) {

/*        Prime machines:  ASCII+128 */

	if (ic >= 225 && ic <= 250) {
	    *(unsigned char *)subnam = (char) (ic - 32);
	    for (i = 2; i <= 6; ++i) {
		ic = *(unsigned char *)&subnam[i - 1];
		if (ic >= 225 && ic <= 250) {
		    *(unsigned char *)&subnam[i - 1] = (char) (ic - 32);
		}
/* L30: */
	    }
	}
    }

    *(unsigned char *)c1 = *(unsigned char *)subnam;
    sname = *(unsigned char *)c1 == 'S' || *(unsigned char *)c1 == 'D';
    cname = *(unsigned char *)c1 == 'C' || *(unsigned char *)c1 == 'Z';
    if (! (cname || sname)) {
	return ret_val;
    }
    s_copy(c2, subnam + 1, 2L, 2L);
    s_copy(c3, subnam + 3, 3L, 3L);
    s_copy(c4, c3 + 1, 2L, 2L);

    switch (*ispec) {
	case 1:  goto L110;
	case 2:  goto L200;
	case 3:  goto L300;
    }

L110:

/*     ISPEC = 1:  block size   

       In these examples, separate code is provided for setting NB for   
       real and complex.  We assume that NB will take the same value in   
       single or double precision. */

    nb = 1;

    if (s_cmp(c2, "GE", 2L, 2L) == 0) {
	if (s_cmp(c3, "TRF", 3L, 3L) == 0) {
	    if (sname) {
		nb = 64;
	    } else {
		nb = 64;
	    }
	} else if (s_cmp(c3, "QRF", 3L, 3L) == 0 || s_cmp(c3, "RQF", 3L, 3L) 
		== 0 || s_cmp(c3, "LQF", 3L, 3L) == 0 || s_cmp(c3, "QLF", 3L, 
		3L) == 0) {
	    if (sname) {
		nb = 32;
	    } else {
		nb = 32;
	    }
	} else if (s_cmp(c3, "HRD", 3L, 3L) == 0) {
	    if (sname) {
		nb = 32;
	    } else {
		nb = 32;
	    }
	} else if (s_cmp(c3, "BRD", 3L, 3L) == 0) {
	    if (sname) {
		nb = 32;
	    } else {
		nb = 32;
	    }
	} else if (s_cmp(c3, "TRI", 3L, 3L) == 0) {
	    if (sname) {
		nb = 64;
	    } else {
		nb = 64;
	    }
	}
    } else if (s_cmp(c2, "PO", 2L, 2L) == 0) {
	if (s_cmp(c3, "TRF", 3L, 3L) == 0) {
	    if (sname) {
		nb = 64;
	    } else {
		nb = 64;
	    }
	}
    } else if (s_cmp(c2, "SY", 2L, 2L) == 0) {
	if (s_cmp(c3, "TRF", 3L, 3L) == 0) {
	    if (sname) {
		nb = 64;
	    } else {
		nb = 64;
	    }