diff options
author | shmel1k <shmel1k@ydb.tech> | 2022-09-02 12:44:59 +0300 |
---|---|---|
committer | shmel1k <shmel1k@ydb.tech> | 2022-09-02 12:44:59 +0300 |
commit | 90d450f74722da7859d6f510a869f6c6908fd12f (patch) | |
tree | 538c718dedc76cdfe37ad6d01ff250dd930d9278 /contrib/libs/clapack/slasd4.c | |
parent | 01f64c1ecd0d4ffa9e3a74478335f1745f26cc75 (diff) | |
download | ydb-90d450f74722da7859d6f510a869f6c6908fd12f.tar.gz |
[] add metering mode to CLI
Diffstat (limited to 'contrib/libs/clapack/slasd4.c')
-rw-r--r-- | contrib/libs/clapack/slasd4.c | 1010 |
1 files changed, 1010 insertions, 0 deletions
diff --git a/contrib/libs/clapack/slasd4.c b/contrib/libs/clapack/slasd4.c new file mode 100644 index 0000000000..11ba6d23c6 --- /dev/null +++ b/contrib/libs/clapack/slasd4.c @@ -0,0 +1,1010 @@ +/* slasd4.f -- translated by f2c (version 20061008). + You must link the resulting object file with libf2c: + on Microsoft Windows system, link with libf2c.lib; + on Linux or Unix systems, link with .../path/to/libf2c.a -lm + or, if you install libf2c.a in a standard place, with -lf2c -lm + -- in that order, at the end of the command line, as in + cc *.o -lf2c -lm + Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., + + http://www.netlib.org/f2c/libf2c.zip +*/ + +#include "f2c.h" +#include "blaswrap.h" + +/* Subroutine */ int slasd4_(integer *n, integer *i__, real *d__, real *z__, + real *delta, real *rho, real *sigma, real *work, integer *info) +{ + /* System generated locals */ + integer i__1; + real r__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + real a, b, c__; + integer j; + real w, dd[3]; + integer ii; + real dw, zz[3]; + integer ip1; + real eta, phi, eps, tau, psi; + integer iim1, iip1; + real dphi, dpsi; + integer iter; + real temp, prew, sg2lb, sg2ub, temp1, temp2, dtiim, delsq, dtiip; + integer niter; + real dtisq; + logical swtch; + real dtnsq; + extern /* Subroutine */ int slaed6_(integer *, logical *, real *, real *, + real *, real *, real *, integer *); + real delsq2; + extern /* Subroutine */ int slasd5_(integer *, real *, real *, real *, + real *, real *, real *); + real dtnsq1; + logical swtch3; + extern doublereal slamch_(char *); + logical orgati; + real erretm, dtipsq, rhoinv; + + +/* -- LAPACK auxiliary routine (version 3.2) -- */ +/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ +/* November 2006 */ + +/* .. Scalar Arguments .. */ +/* .. */ +/* .. Array Arguments .. */ +/* .. */ + +/* Purpose */ +/* ======= */ + +/* This subroutine computes the square root of the I-th updated */ +/* eigenvalue of a positive symmetric rank-one modification to */ +/* a positive diagonal matrix whose entries are given as the squares */ +/* of the corresponding entries in the array d, and that */ + +/* 0 <= D(i) < D(j) for i < j */ + +/* and that RHO > 0. This is arranged by the calling routine, and is */ +/* no loss in generality. The rank-one modified system is thus */ + +/* diag( D ) * diag( D ) + RHO * Z * Z_transpose. */ + +/* where we assume the Euclidean norm of Z is 1. */ + +/* The method consists of approximating the rational functions in the */ +/* secular equation by simpler interpolating rational functions. */ + +/* Arguments */ +/* ========= */ + +/* N (input) INTEGER */ +/* The length of all arrays. */ + +/* I (input) INTEGER */ +/* The index of the eigenvalue to be computed. 1 <= I <= N. */ + +/* D (input) REAL array, dimension ( N ) */ +/* The original eigenvalues. It is assumed that they are in */ +/* order, 0 <= D(I) < D(J) for I < J. */ + +/* Z (input) REAL array, dimension (N) */ +/* The components of the updating vector. */ + +/* DELTA (output) REAL array, dimension (N) */ +/* If N .ne. 1, DELTA contains (D(j) - sigma_I) in its j-th */ +/* component. If N = 1, then DELTA(1) = 1. The vector DELTA */ +/* contains the information necessary to construct the */ +/* (singular) eigenvectors. */ + +/* RHO (input) REAL */ +/* The scalar in the symmetric updating formula. */ + +/* SIGMA (output) REAL */ +/* The computed sigma_I, the I-th updated eigenvalue. */ + +/* WORK (workspace) REAL array, dimension (N) */ +/* If N .ne. 1, WORK contains (D(j) + sigma_I) in its j-th */ +/* component. If N = 1, then WORK( 1 ) = 1. */ + +/* INFO (output) INTEGER */ +/* = 0: successful exit */ +/* > 0: if INFO = 1, the updating process failed. */ + +/* Internal Parameters */ +/* =================== */ + +/* Logical variable ORGATI (origin-at-i?) is used for distinguishing */ +/* whether D(i) or D(i+1) is treated as the origin. */ + +/* ORGATI = .true. origin at i */ +/* ORGATI = .false. origin at i+1 */ + +/* Logical variable SWTCH3 (switch-for-3-poles?) is for noting */ +/* if we are working with THREE poles! */ + +/* MAXIT is the maximum number of iterations allowed for each */ +/* eigenvalue. */ + +/* Further Details */ +/* =============== */ + +/* Based on contributions by */ +/* Ren-Cang Li, Computer Science Division, University of California */ +/* at Berkeley, USA */ + +/* ===================================================================== */ + +/* .. Parameters .. */ +/* .. */ +/* .. Local Scalars .. */ +/* .. */ +/* .. Local Arrays .. */ +/* .. */ +/* .. External Subroutines .. */ +/* .. */ +/* .. External Functions .. */ +/* .. */ +/* .. Intrinsic Functions .. */ +/* .. */ +/* .. Executable Statements .. */ + +/* Since this routine is called in an inner loop, we do no argument */ +/* checking. */ + +/* Quick return for N=1 and 2. */ + + /* Parameter adjustments */ + --work; + --delta; + --z__; + --d__; + + /* Function Body */ + *info = 0; + if (*n == 1) { + +/* Presumably, I=1 upon entry */ + + *sigma = sqrt(d__[1] * d__[1] + *rho * z__[1] * z__[1]); + delta[1] = 1.f; + work[1] = 1.f; + return 0; + } + if (*n == 2) { + slasd5_(i__, &d__[1], &z__[1], &delta[1], rho, sigma, &work[1]); + return 0; + } + +/* Compute machine epsilon */ + + eps = slamch_("Epsilon"); + rhoinv = 1.f / *rho; + +/* The case I = N */ + + if (*i__ == *n) { + +/* Initialize some basic variables */ + + ii = *n - 1; + niter = 1; + +/* Calculate initial guess */ + + temp = *rho / 2.f; + +/* If ||Z||_2 is not one, then TEMP should be set to */ +/* RHO * ||Z||_2^2 / TWO */ + + temp1 = temp / (d__[*n] + sqrt(d__[*n] * d__[*n] + temp)); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[*n] + temp1; + delta[j] = d__[j] - d__[*n] - temp1; +/* L10: */ + } + + psi = 0.f; + i__1 = *n - 2; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / (delta[j] * work[j]); +/* L20: */ + } + + c__ = rhoinv + psi; + w = c__ + z__[ii] * z__[ii] / (delta[ii] * work[ii]) + z__[*n] * z__[* + n] / (delta[*n] * work[*n]); + + if (w <= 0.f) { + temp1 = sqrt(d__[*n] * d__[*n] + *rho); + temp = z__[*n - 1] * z__[*n - 1] / ((d__[*n - 1] + temp1) * (d__[* + n] - d__[*n - 1] + *rho / (d__[*n] + temp1))) + z__[*n] * + z__[*n] / *rho; + +/* The following TAU is to approximate */ +/* SIGMA_n^2 - D( N )*D( N ) */ + + if (c__ <= temp) { + tau = *rho; + } else { + delsq = (d__[*n] - d__[*n - 1]) * (d__[*n] + d__[*n - 1]); + a = -c__ * delsq + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[* + n]; + b = z__[*n] * z__[*n] * delsq; + if (a < 0.f) { + tau = b * 2.f / (sqrt(a * a + b * 4.f * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4.f * c__)) / (c__ * 2.f); + } + } + +/* It can be proved that */ +/* D(N)^2+RHO/2 <= SIGMA_n^2 < D(N)^2+TAU <= D(N)^2+RHO */ + + } else { + delsq = (d__[*n] - d__[*n - 1]) * (d__[*n] + d__[*n - 1]); + a = -c__ * delsq + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[*n]; + b = z__[*n] * z__[*n] * delsq; + +/* The following TAU is to approximate */ +/* SIGMA_n^2 - D( N )*D( N ) */ + + if (a < 0.f) { + tau = b * 2.f / (sqrt(a * a + b * 4.f * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4.f * c__)) / (c__ * 2.f); + } + +/* It can be proved that */ +/* D(N)^2 < D(N)^2+TAU < SIGMA(N)^2 < D(N)^2+RHO/2 */ + + } + +/* The following ETA is to approximate SIGMA_n - D( N ) */ + + eta = tau / (d__[*n] + sqrt(d__[*n] * d__[*n] + tau)); + + *sigma = d__[*n] + eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - eta; + work[j] = d__[j] + d__[*i__] + eta; +/* L30: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (delta[j] * work[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L40: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / (delta[*n] * work[*n]); + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * ( + dpsi + dphi); + + w = rhoinv + phi + psi; + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + +/* Calculate the new step */ + + ++niter; + dtnsq1 = work[*n - 1] * delta[*n - 1]; + dtnsq = work[*n] * delta[*n]; + c__ = w - dtnsq1 * dpsi - dtnsq * dphi; + a = (dtnsq + dtnsq1) * w - dtnsq * dtnsq1 * (dpsi + dphi); + b = dtnsq * dtnsq1 * w; + if (c__ < 0.f) { + c__ = dabs(c__); + } + if (c__ == 0.f) { + eta = *rho - *sigma * *sigma; + } else if (a >= 0.f) { + eta = (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / ( + c__ * 2.f); + } else { + eta = b * 2.f / (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + +/* Note, eta should be positive if w is negative, and */ +/* eta should be negative otherwise. However, */ +/* if for some reason caused by roundoff, eta*w > 0, */ +/* we simply use one Newton step instead. This way */ +/* will guarantee eta*w < 0. */ + + if (w * eta > 0.f) { + eta = -w / (dpsi + dphi); + } + temp = eta - dtnsq; + if (temp > *rho) { + eta = *rho + dtnsq; + } + + tau += eta; + eta /= *sigma + sqrt(eta + *sigma * *sigma); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; + work[j] += eta; +/* L50: */ + } + + *sigma += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L60: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / (work[*n] * delta[*n]); + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * ( + dpsi + dphi); + + w = rhoinv + phi + psi; + +/* Main loop to update the values of the array DELTA */ + + iter = niter + 1; + + for (niter = iter; niter <= 20; ++niter) { + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + +/* Calculate the new step */ + + dtnsq1 = work[*n - 1] * delta[*n - 1]; + dtnsq = work[*n] * delta[*n]; + c__ = w - dtnsq1 * dpsi - dtnsq * dphi; + a = (dtnsq + dtnsq1) * w - dtnsq1 * dtnsq * (dpsi + dphi); + b = dtnsq1 * dtnsq * w; + if (a >= 0.f) { + eta = (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } else { + eta = b * 2.f / (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + +/* Note, eta should be positive if w is negative, and */ +/* eta should be negative otherwise. However, */ +/* if for some reason caused by roundoff, eta*w > 0, */ +/* we simply use one Newton step instead. This way */ +/* will guarantee eta*w < 0. */ + + if (w * eta > 0.f) { + eta = -w / (dpsi + dphi); + } + temp = eta - dtnsq; + if (temp <= 0.f) { + eta /= 2.f; + } + + tau += eta; + eta /= *sigma + sqrt(eta + *sigma * *sigma); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; + work[j] += eta; +/* L70: */ + } + + *sigma += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L80: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / (work[*n] * delta[*n]); + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8.f + erretm - phi + rhoinv + dabs(tau) * + (dpsi + dphi); + + w = rhoinv + phi + psi; +/* L90: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + goto L240; + +/* End for the case I = N */ + + } else { + +/* The case for I < N */ + + niter = 1; + ip1 = *i__ + 1; + +/* Calculate initial guess */ + + delsq = (d__[ip1] - d__[*i__]) * (d__[ip1] + d__[*i__]); + delsq2 = delsq / 2.f; + temp = delsq2 / (d__[*i__] + sqrt(d__[*i__] * d__[*i__] + delsq2)); + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[*i__] + temp; + delta[j] = d__[j] - d__[*i__] - temp; +/* L100: */ + } + + psi = 0.f; + i__1 = *i__ - 1; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / (work[j] * delta[j]); +/* L110: */ + } + + phi = 0.f; + i__1 = *i__ + 2; + for (j = *n; j >= i__1; --j) { + phi += z__[j] * z__[j] / (work[j] * delta[j]); +/* L120: */ + } + c__ = rhoinv + psi + phi; + w = c__ + z__[*i__] * z__[*i__] / (work[*i__] * delta[*i__]) + z__[ + ip1] * z__[ip1] / (work[ip1] * delta[ip1]); + + if (w > 0.f) { + +/* d(i)^2 < the ith sigma^2 < (d(i)^2+d(i+1)^2)/2 */ + +/* We choose d(i) as origin. */ + + orgati = TRUE_; + sg2lb = 0.f; + sg2ub = delsq2; + a = c__ * delsq + z__[*i__] * z__[*i__] + z__[ip1] * z__[ip1]; + b = z__[*i__] * z__[*i__] * delsq; + if (a > 0.f) { + tau = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } else { + tau = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } + +/* TAU now is an estimation of SIGMA^2 - D( I )^2. The */ +/* following, however, is the corresponding estimation of */ +/* SIGMA - D( I ). */ + + eta = tau / (d__[*i__] + sqrt(d__[*i__] * d__[*i__] + tau)); + } else { + +/* (d(i)^2+d(i+1)^2)/2 <= the ith sigma^2 < d(i+1)^2/2 */ + +/* We choose d(i+1) as origin. */ + + orgati = FALSE_; + sg2lb = -delsq2; + sg2ub = 0.f; + a = c__ * delsq - z__[*i__] * z__[*i__] - z__[ip1] * z__[ip1]; + b = z__[ip1] * z__[ip1] * delsq; + if (a < 0.f) { + tau = b * 2.f / (a - sqrt((r__1 = a * a + b * 4.f * c__, dabs( + r__1)))); + } else { + tau = -(a + sqrt((r__1 = a * a + b * 4.f * c__, dabs(r__1)))) + / (c__ * 2.f); + } + +/* TAU now is an estimation of SIGMA^2 - D( IP1 )^2. The */ +/* following, however, is the corresponding estimation of */ +/* SIGMA - D( IP1 ). */ + + eta = tau / (d__[ip1] + sqrt((r__1 = d__[ip1] * d__[ip1] + tau, + dabs(r__1)))); + } + + if (orgati) { + ii = *i__; + *sigma = d__[*i__] + eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[*i__] + eta; + delta[j] = d__[j] - d__[*i__] - eta; +/* L130: */ + } + } else { + ii = *i__ + 1; + *sigma = d__[ip1] + eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] = d__[j] + d__[ip1] + eta; + delta[j] = d__[j] - d__[ip1] - eta; +/* L140: */ + } + } + iim1 = ii - 1; + iip1 = ii + 1; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L150: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / (work[j] * delta[j]); + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L160: */ + } + + w = rhoinv + phi + psi; + +/* W is the value of the secular function with */ +/* its ii-th element removed. */ + + swtch3 = FALSE_; + if (orgati) { + if (w < 0.f) { + swtch3 = TRUE_; + } + } else { + if (w > 0.f) { + swtch3 = TRUE_; + } + } + if (ii == 1 || ii == *n) { + swtch3 = FALSE_; + } + + temp = z__[ii] / (work[ii] * delta[ii]); + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w += temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * 3.f + + dabs(tau) * dw; + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + + if (w <= 0.f) { + sg2lb = dmax(sg2lb,tau); + } else { + sg2ub = dmin(sg2ub,tau); + } + +/* Calculate the new step */ + + ++niter; + if (! swtch3) { + dtipsq = work[ip1] * delta[ip1]; + dtisq = work[*i__] * delta[*i__]; + if (orgati) { +/* Computing 2nd power */ + r__1 = z__[*i__] / dtisq; + c__ = w - dtipsq * dw + delsq * (r__1 * r__1); + } else { +/* Computing 2nd power */ + r__1 = z__[ip1] / dtipsq; + c__ = w - dtisq * dw - delsq * (r__1 * r__1); + } + a = (dtipsq + dtisq) * w - dtipsq * dtisq * dw; + b = dtipsq * dtisq * w; + if (c__ == 0.f) { + if (a == 0.f) { + if (orgati) { + a = z__[*i__] * z__[*i__] + dtipsq * dtipsq * (dpsi + + dphi); + } else { + a = z__[ip1] * z__[ip1] + dtisq * dtisq * (dpsi + + dphi); + } + } + eta = b / a; + } else if (a <= 0.f) { + eta = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)))) / + (c__ * 2.f); + } else { + eta = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, dabs( + r__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + dtiim = work[iim1] * delta[iim1]; + dtiip = work[iip1] * delta[iip1]; + temp = rhoinv + psi + phi; + if (orgati) { + temp1 = z__[iim1] / dtiim; + temp1 *= temp1; + c__ = temp - dtiip * (dpsi + dphi) - (d__[iim1] - d__[iip1]) * + (d__[iim1] + d__[iip1]) * temp1; + zz[0] = z__[iim1] * z__[iim1]; + if (dpsi < temp1) { + zz[2] = dtiip * dtiip * dphi; + } else { + zz[2] = dtiip * dtiip * (dpsi - temp1 + dphi); + } + } else { + temp1 = z__[iip1] / dtiip; + temp1 *= temp1; + c__ = temp - dtiim * (dpsi + dphi) - (d__[iip1] - d__[iim1]) * + (d__[iim1] + d__[iip1]) * temp1; + if (dphi < temp1) { + zz[0] = dtiim * dtiim * dpsi; + } else { + zz[0] = dtiim * dtiim * (dpsi + (dphi - temp1)); + } + zz[2] = z__[iip1] * z__[iip1]; + } + zz[1] = z__[ii] * z__[ii]; + dd[0] = dtiim; + dd[1] = delta[ii] * work[ii]; + dd[2] = dtiip; + slaed6_(&niter, &orgati, &c__, dd, zz, &w, &eta, info); + if (*info != 0) { + goto L240; + } + } + +/* Note, eta should be positive if w is negative, and */ +/* eta should be negative otherwise. However, */ +/* if for some reason caused by roundoff, eta*w > 0, */ +/* we simply use one Newton step instead. This way */ +/* will guarantee eta*w < 0. */ + + if (w * eta >= 0.f) { + eta = -w / dw; + } + if (orgati) { + temp1 = work[*i__] * delta[*i__]; + temp = eta - temp1; + } else { + temp1 = work[ip1] * delta[ip1]; + temp = eta - temp1; + } + if (temp > sg2ub || temp < sg2lb) { + if (w < 0.f) { + eta = (sg2ub - tau) / 2.f; + } else { + eta = (sg2lb - tau) / 2.f; + } + } + + tau += eta; + eta /= *sigma + sqrt(*sigma * *sigma + eta); + + prew = w; + + *sigma += eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] += eta; + delta[j] -= eta; +/* L170: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L180: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / (work[j] * delta[j]); + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L190: */ + } + + temp = z__[ii] / (work[ii] * delta[ii]); + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * 3.f + + dabs(tau) * dw; + + if (w <= 0.f) { + sg2lb = dmax(sg2lb,tau); + } else { + sg2ub = dmin(sg2ub,tau); + } + + swtch = FALSE_; + if (orgati) { + if (-w > dabs(prew) / 10.f) { + swtch = TRUE_; + } + } else { + if (w > dabs(prew) / 10.f) { + swtch = TRUE_; + } + } + +/* Main loop to update the values of the array DELTA and WORK */ + + iter = niter + 1; + + for (niter = iter; niter <= 20; ++niter) { + +/* Test for convergence */ + + if (dabs(w) <= eps * erretm) { + goto L240; + } + +/* Calculate the new step */ + + if (! swtch3) { + dtipsq = work[ip1] * delta[ip1]; + dtisq = work[*i__] * delta[*i__]; + if (! swtch) { + if (orgati) { +/* Computing 2nd power */ + r__1 = z__[*i__] / dtisq; + c__ = w - dtipsq * dw + delsq * (r__1 * r__1); + } else { +/* Computing 2nd power */ + r__1 = z__[ip1] / dtipsq; + c__ = w - dtisq * dw - delsq * (r__1 * r__1); + } + } else { + temp = z__[ii] / (work[ii] * delta[ii]); + if (orgati) { + dpsi += temp * temp; + } else { + dphi += temp * temp; + } + c__ = w - dtisq * dpsi - dtipsq * dphi; + } + a = (dtipsq + dtisq) * w - dtipsq * dtisq * dw; + b = dtipsq * dtisq * w; + if (c__ == 0.f) { + if (a == 0.f) { + if (! swtch) { + if (orgati) { + a = z__[*i__] * z__[*i__] + dtipsq * dtipsq * + (dpsi + dphi); + } else { + a = z__[ip1] * z__[ip1] + dtisq * dtisq * ( + dpsi + dphi); + } + } else { + a = dtisq * dtisq * dpsi + dtipsq * dtipsq * dphi; + } + } + eta = b / a; + } else if (a <= 0.f) { + eta = (a - sqrt((r__1 = a * a - b * 4.f * c__, dabs(r__1)) + )) / (c__ * 2.f); + } else { + eta = b * 2.f / (a + sqrt((r__1 = a * a - b * 4.f * c__, + dabs(r__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + dtiim = work[iim1] * delta[iim1]; + dtiip = work[iip1] * delta[iip1]; + temp = rhoinv + psi + phi; + if (swtch) { + c__ = temp - dtiim * dpsi - dtiip * dphi; + zz[0] = dtiim * dtiim * dpsi; + zz[2] = dtiip * dtiip * dphi; + } else { + if (orgati) { + temp1 = z__[iim1] / dtiim; + temp1 *= temp1; + temp2 = (d__[iim1] - d__[iip1]) * (d__[iim1] + d__[ + iip1]) * temp1; + c__ = temp - dtiip * (dpsi + dphi) - temp2; + zz[0] = z__[iim1] * z__[iim1]; + if (dpsi < temp1) { + zz[2] = dtiip * dtiip * dphi; + } else { + zz[2] = dtiip * dtiip * (dpsi - temp1 + dphi); + } + } else { + temp1 = z__[iip1] / dtiip; + temp1 *= temp1; + temp2 = (d__[iip1] - d__[iim1]) * (d__[iim1] + d__[ + iip1]) * temp1; + c__ = temp - dtiim * (dpsi + dphi) - temp2; + if (dphi < temp1) { + zz[0] = dtiim * dtiim * dpsi; + } else { + zz[0] = dtiim * dtiim * (dpsi + (dphi - temp1)); + } + zz[2] = z__[iip1] * z__[iip1]; + } + } + dd[0] = dtiim; + dd[1] = delta[ii] * work[ii]; + dd[2] = dtiip; + slaed6_(&niter, &orgati, &c__, dd, zz, &w, &eta, info); + if (*info != 0) { + goto L240; + } + } + +/* Note, eta should be positive if w is negative, and */ +/* eta should be negative otherwise. However, */ +/* if for some reason caused by roundoff, eta*w > 0, */ +/* we simply use one Newton step instead. This way */ +/* will guarantee eta*w < 0. */ + + if (w * eta >= 0.f) { + eta = -w / dw; + } + if (orgati) { + temp1 = work[*i__] * delta[*i__]; + temp = eta - temp1; + } else { + temp1 = work[ip1] * delta[ip1]; + temp = eta - temp1; + } + if (temp > sg2ub || temp < sg2lb) { + if (w < 0.f) { + eta = (sg2ub - tau) / 2.f; + } else { + eta = (sg2lb - tau) / 2.f; + } + } + + tau += eta; + eta /= *sigma + sqrt(*sigma * *sigma + eta); + + *sigma += eta; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + work[j] += eta; + delta[j] -= eta; +/* L200: */ + } + + prew = w; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.f; + psi = 0.f; + erretm = 0.f; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / (work[j] * delta[j]); + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L210: */ + } + erretm = dabs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.f; + phi = 0.f; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / (work[j] * delta[j]); + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L220: */ + } + + temp = z__[ii] / (work[ii] * delta[ii]); + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8.f + erretm + rhoinv * 2.f + dabs(temp) * + 3.f + dabs(tau) * dw; + if (w * prew > 0.f && dabs(w) > dabs(prew) / 10.f) { + swtch = ! swtch; + } + + if (w <= 0.f) { + sg2lb = dmax(sg2lb,tau); + } else { + sg2ub = dmin(sg2ub,tau); + } + +/* L230: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + + } + +L240: + return 0; + +/* End of SLASD4 */ + +} /* slasd4_ */ |