X-Git-Url: https://vcs.maemo.org/git/?a=blobdiff_plain;f=3rdparty%2Flapack%2Fdlaed4.c;fp=3rdparty%2Flapack%2Fdlaed4.c;h=1a3686f0bfbf83e1479f40ae685ab84b4daf1153;hb=e4c14cdbdf2fe805e79cd96ded236f57e7b89060;hp=0000000000000000000000000000000000000000;hpb=454138ff8a20f6edb9b65a910101403d8b520643;p=opencv diff --git a/3rdparty/lapack/dlaed4.c b/3rdparty/lapack/dlaed4.c new file mode 100644 index 0000000..1a3686f --- /dev/null +++ b/3rdparty/lapack/dlaed4.c @@ -0,0 +1,941 @@ +#include "clapack.h" + +/* Subroutine */ int dlaed4_(integer *n, integer *i__, doublereal *d__, + doublereal *z__, doublereal *delta, doublereal *rho, doublereal *dlam, + integer *info) +{ + /* System generated locals */ + integer i__1; + doublereal d__1; + + /* Builtin functions */ + double sqrt(doublereal); + + /* Local variables */ + doublereal a, b, c__; + integer j; + doublereal w; + integer ii; + doublereal dw, zz[3]; + integer ip1; + doublereal del, eta, phi, eps, tau, psi; + integer iim1, iip1; + doublereal dphi, dpsi; + integer iter; + doublereal temp, prew, temp1, dltlb, dltub, midpt; + integer niter; + logical swtch; + extern /* Subroutine */ int dlaed5_(integer *, doublereal *, doublereal *, + doublereal *, doublereal *, doublereal *), dlaed6_(integer *, + logical *, doublereal *, doublereal *, doublereal *, doublereal *, + doublereal *, integer *); + logical swtch3; + extern doublereal dlamch_(char *); + logical orgati; + doublereal erretm, rhoinv; + + +/* -- LAPACK routine (version 3.1) -- */ +/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ +/* November 2006 */ + +/* .. Scalar Arguments .. */ +/* .. */ +/* .. Array Arguments .. */ +/* .. */ + +/* Purpose */ +/* ======= */ + +/* This subroutine computes the I-th updated eigenvalue of a symmetric */ +/* rank-one modification to a diagonal matrix whose elements are */ +/* given in the array d, and that */ + +/* 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 ) + 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) DOUBLE PRECISION array, dimension (N) */ +/* The original eigenvalues. It is assumed that they are in */ +/* order, D(I) < D(J) for I < J. */ + +/* Z (input) DOUBLE PRECISION array, dimension (N) */ +/* The components of the updating vector. */ + +/* DELTA (output) DOUBLE PRECISION array, dimension (N) */ +/* If N .GT. 2, DELTA contains (D(j) - lambda_I) in its j-th */ +/* component. If N = 1, then DELTA(1) = 1. If N = 2, see DLAED5 */ +/* for detail. The vector DELTA contains the information necessary */ +/* to construct the eigenvectors by DLAED3 and DLAED9. */ + +/* RHO (input) DOUBLE PRECISION */ +/* The scalar in the symmetric updating formula. */ + +/* DLAM (output) DOUBLE PRECISION */ +/* The computed lambda_I, the I-th updated eigenvalue. */ + +/* 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 Functions .. */ +/* .. */ +/* .. External Subroutines .. */ +/* .. */ +/* .. 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 */ + --delta; + --z__; + --d__; + + /* Function Body */ + *info = 0; + if (*n == 1) { + +/* Presumably, I=1 upon entry */ + + *dlam = d__[1] + *rho * z__[1] * z__[1]; + delta[1] = 1.; + return 0; + } + if (*n == 2) { + dlaed5_(i__, &d__[1], &z__[1], &delta[1], rho, dlam); + return 0; + } + +/* Compute machine epsilon */ + + eps = dlamch_("Epsilon"); + rhoinv = 1. / *rho; + +/* The case I = N */ + + if (*i__ == *n) { + +/* Initialize some basic variables */ + + ii = *n - 1; + niter = 1; + +/* Calculate initial guess */ + + midpt = *rho / 2.; + +/* If ||Z||_2 is not one, then TEMP should be set to */ +/* RHO * ||Z||_2^2 / TWO */ + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - midpt; +/* L10: */ + } + + psi = 0.; + i__1 = *n - 2; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / delta[j]; +/* L20: */ + } + + c__ = rhoinv + psi; + w = c__ + z__[ii] * z__[ii] / delta[ii] + z__[*n] * z__[*n] / delta[* + n]; + + if (w <= 0.) { + temp = z__[*n - 1] * z__[*n - 1] / (d__[*n] - d__[*n - 1] + *rho) + + z__[*n] * z__[*n] / *rho; + if (c__ <= temp) { + tau = *rho; + } else { + del = d__[*n] - d__[*n - 1]; + a = -c__ * del + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[*n] + ; + b = z__[*n] * z__[*n] * del; + if (a < 0.) { + tau = b * 2. / (sqrt(a * a + b * 4. * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4. * c__)) / (c__ * 2.); + } + } + +/* It can be proved that */ +/* D(N)+RHO/2 <= LAMBDA(N) < D(N)+TAU <= D(N)+RHO */ + + dltlb = midpt; + dltub = *rho; + } else { + del = d__[*n] - d__[*n - 1]; + a = -c__ * del + z__[*n - 1] * z__[*n - 1] + z__[*n] * z__[*n]; + b = z__[*n] * z__[*n] * del; + if (a < 0.) { + tau = b * 2. / (sqrt(a * a + b * 4. * c__) - a); + } else { + tau = (a + sqrt(a * a + b * 4. * c__)) / (c__ * 2.); + } + +/* It can be proved that */ +/* D(N) < D(N)+TAU < LAMBDA(N) < D(N)+RHO/2 */ + + dltlb = 0.; + dltub = midpt; + } + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - tau; +/* L30: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.; + psi = 0.; + erretm = 0.; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L40: */ + } + erretm = abs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / delta[*n]; + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8. + erretm - phi + rhoinv + abs(tau) * (dpsi + + dphi); + + w = rhoinv + phi + psi; + +/* Test for convergence */ + + if (abs(w) <= eps * erretm) { + *dlam = d__[*i__] + tau; + goto L250; + } + + if (w <= 0.) { + dltlb = max(dltlb,tau); + } else { + dltub = min(dltub,tau); + } + +/* Calculate the new step */ + + ++niter; + c__ = w - delta[*n - 1] * dpsi - delta[*n] * dphi; + a = (delta[*n - 1] + delta[*n]) * w - delta[*n - 1] * delta[*n] * ( + dpsi + dphi); + b = delta[*n - 1] * delta[*n] * w; + if (c__ < 0.) { + c__ = abs(c__); + } + if (c__ == 0.) { +/* ETA = B/A */ +/* ETA = RHO - TAU */ + eta = dltub - tau; + } else if (a >= 0.) { + eta = (a + sqrt((d__1 = a * a - b * 4. * c__, abs(d__1)))) / (c__ + * 2.); + } else { + eta = b * 2. / (a - sqrt((d__1 = a * a - b * 4. * c__, abs(d__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.) { + eta = -w / (dpsi + dphi); + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.) { + eta = (dltub - tau) / 2.; + } else { + eta = (dltlb - tau) / 2.; + } + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L50: */ + } + + tau += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.; + psi = 0.; + erretm = 0.; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L60: */ + } + erretm = abs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / delta[*n]; + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8. + erretm - phi + rhoinv + abs(tau) * (dpsi + + dphi); + + w = rhoinv + phi + psi; + +/* Main loop to update the values of the array DELTA */ + + iter = niter + 1; + + for (niter = iter; niter <= 30; ++niter) { + +/* Test for convergence */ + + if (abs(w) <= eps * erretm) { + *dlam = d__[*i__] + tau; + goto L250; + } + + if (w <= 0.) { + dltlb = max(dltlb,tau); + } else { + dltub = min(dltub,tau); + } + +/* Calculate the new step */ + + c__ = w - delta[*n - 1] * dpsi - delta[*n] * dphi; + a = (delta[*n - 1] + delta[*n]) * w - delta[*n - 1] * delta[*n] * + (dpsi + dphi); + b = delta[*n - 1] * delta[*n] * w; + if (a >= 0.) { + eta = (a + sqrt((d__1 = a * a - b * 4. * c__, abs(d__1)))) / ( + c__ * 2.); + } else { + eta = b * 2. / (a - sqrt((d__1 = a * a - b * 4. * c__, abs( + d__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.) { + eta = -w / (dpsi + dphi); + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.) { + eta = (dltub - tau) / 2.; + } else { + eta = (dltlb - tau) / 2.; + } + } + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L70: */ + } + + tau += eta; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.; + psi = 0.; + erretm = 0.; + i__1 = ii; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L80: */ + } + erretm = abs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + temp = z__[*n] / delta[*n]; + phi = z__[*n] * temp; + dphi = temp * temp; + erretm = (-phi - psi) * 8. + erretm - phi + rhoinv + abs(tau) * ( + dpsi + dphi); + + w = rhoinv + phi + psi; +/* L90: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + *dlam = d__[*i__] + tau; + goto L250; + +/* End for the case I = N */ + + } else { + +/* The case for I < N */ + + niter = 1; + ip1 = *i__ + 1; + +/* Calculate initial guess */ + + del = d__[ip1] - d__[*i__]; + midpt = del / 2.; + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - midpt; +/* L100: */ + } + + psi = 0.; + i__1 = *i__ - 1; + for (j = 1; j <= i__1; ++j) { + psi += z__[j] * z__[j] / delta[j]; +/* L110: */ + } + + phi = 0.; + i__1 = *i__ + 2; + for (j = *n; j >= i__1; --j) { + phi += z__[j] * z__[j] / delta[j]; +/* L120: */ + } + c__ = rhoinv + psi + phi; + w = c__ + z__[*i__] * z__[*i__] / delta[*i__] + z__[ip1] * z__[ip1] / + delta[ip1]; + + if (w > 0.) { + +/* d(i)< the ith eigenvalue < (d(i)+d(i+1))/2 */ + +/* We choose d(i) as origin. */ + + orgati = TRUE_; + a = c__ * del + z__[*i__] * z__[*i__] + z__[ip1] * z__[ip1]; + b = z__[*i__] * z__[*i__] * del; + if (a > 0.) { + tau = b * 2. / (a + sqrt((d__1 = a * a - b * 4. * c__, abs( + d__1)))); + } else { + tau = (a - sqrt((d__1 = a * a - b * 4. * c__, abs(d__1)))) / ( + c__ * 2.); + } + dltlb = 0.; + dltub = midpt; + } else { + +/* (d(i)+d(i+1))/2 <= the ith eigenvalue < d(i+1) */ + +/* We choose d(i+1) as origin. */ + + orgati = FALSE_; + a = c__ * del - z__[*i__] * z__[*i__] - z__[ip1] * z__[ip1]; + b = z__[ip1] * z__[ip1] * del; + if (a < 0.) { + tau = b * 2. / (a - sqrt((d__1 = a * a + b * 4. * c__, abs( + d__1)))); + } else { + tau = -(a + sqrt((d__1 = a * a + b * 4. * c__, abs(d__1)))) / + (c__ * 2.); + } + dltlb = -midpt; + dltub = 0.; + } + + if (orgati) { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[*i__] - tau; +/* L130: */ + } + } else { + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] = d__[j] - d__[ip1] - tau; +/* L140: */ + } + } + if (orgati) { + ii = *i__; + } else { + ii = *i__ + 1; + } + iim1 = ii - 1; + iip1 = ii + 1; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.; + psi = 0.; + erretm = 0.; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L150: */ + } + erretm = abs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.; + phi = 0.; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[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.) { + swtch3 = TRUE_; + } + } else { + if (w > 0.) { + swtch3 = TRUE_; + } + } + if (ii == 1 || ii == *n) { + swtch3 = FALSE_; + } + + temp = z__[ii] / delta[ii]; + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w += temp; + erretm = (phi - psi) * 8. + erretm + rhoinv * 2. + abs(temp) * 3. + + abs(tau) * dw; + +/* Test for convergence */ + + if (abs(w) <= eps * erretm) { + if (orgati) { + *dlam = d__[*i__] + tau; + } else { + *dlam = d__[ip1] + tau; + } + goto L250; + } + + if (w <= 0.) { + dltlb = max(dltlb,tau); + } else { + dltub = min(dltub,tau); + } + +/* Calculate the new step */ + + ++niter; + if (! swtch3) { + if (orgati) { +/* Computing 2nd power */ + d__1 = z__[*i__] / delta[*i__]; + c__ = w - delta[ip1] * dw - (d__[*i__] - d__[ip1]) * (d__1 * + d__1); + } else { +/* Computing 2nd power */ + d__1 = z__[ip1] / delta[ip1]; + c__ = w - delta[*i__] * dw - (d__[ip1] - d__[*i__]) * (d__1 * + d__1); + } + a = (delta[*i__] + delta[ip1]) * w - delta[*i__] * delta[ip1] * + dw; + b = delta[*i__] * delta[ip1] * w; + if (c__ == 0.) { + if (a == 0.) { + if (orgati) { + a = z__[*i__] * z__[*i__] + delta[ip1] * delta[ip1] * + (dpsi + dphi); + } else { + a = z__[ip1] * z__[ip1] + delta[*i__] * delta[*i__] * + (dpsi + dphi); + } + } + eta = b / a; + } else if (a <= 0.) { + eta = (a - sqrt((d__1 = a * a - b * 4. * c__, abs(d__1)))) / ( + c__ * 2.); + } else { + eta = b * 2. / (a + sqrt((d__1 = a * a - b * 4. * c__, abs( + d__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + temp = rhoinv + psi + phi; + if (orgati) { + temp1 = z__[iim1] / delta[iim1]; + temp1 *= temp1; + c__ = temp - delta[iip1] * (dpsi + dphi) - (d__[iim1] - d__[ + iip1]) * temp1; + zz[0] = z__[iim1] * z__[iim1]; + zz[2] = delta[iip1] * delta[iip1] * (dpsi - temp1 + dphi); + } else { + temp1 = z__[iip1] / delta[iip1]; + temp1 *= temp1; + c__ = temp - delta[iim1] * (dpsi + dphi) - (d__[iip1] - d__[ + iim1]) * temp1; + zz[0] = delta[iim1] * delta[iim1] * (dpsi + (dphi - temp1)); + zz[2] = z__[iip1] * z__[iip1]; + } + zz[1] = z__[ii] * z__[ii]; + dlaed6_(&niter, &orgati, &c__, &delta[iim1], zz, &w, &eta, info); + if (*info != 0) { + goto L250; + } + } + +/* 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.) { + eta = -w / dw; + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.) { + eta = (dltub - tau) / 2.; + } else { + eta = (dltlb - tau) / 2.; + } + } + + prew = w; + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L180: */ + } + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.; + psi = 0.; + erretm = 0.; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L190: */ + } + erretm = abs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.; + phi = 0.; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / delta[j]; + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L200: */ + } + + temp = z__[ii] / delta[ii]; + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8. + erretm + rhoinv * 2. + abs(temp) * 3. + ( + d__1 = tau + eta, abs(d__1)) * dw; + + swtch = FALSE_; + if (orgati) { + if (-w > abs(prew) / 10.) { + swtch = TRUE_; + } + } else { + if (w > abs(prew) / 10.) { + swtch = TRUE_; + } + } + + tau += eta; + +/* Main loop to update the values of the array DELTA */ + + iter = niter + 1; + + for (niter = iter; niter <= 30; ++niter) { + +/* Test for convergence */ + + if (abs(w) <= eps * erretm) { + if (orgati) { + *dlam = d__[*i__] + tau; + } else { + *dlam = d__[ip1] + tau; + } + goto L250; + } + + if (w <= 0.) { + dltlb = max(dltlb,tau); + } else { + dltub = min(dltub,tau); + } + +/* Calculate the new step */ + + if (! swtch3) { + if (! swtch) { + if (orgati) { +/* Computing 2nd power */ + d__1 = z__[*i__] / delta[*i__]; + c__ = w - delta[ip1] * dw - (d__[*i__] - d__[ip1]) * ( + d__1 * d__1); + } else { +/* Computing 2nd power */ + d__1 = z__[ip1] / delta[ip1]; + c__ = w - delta[*i__] * dw - (d__[ip1] - d__[*i__]) * + (d__1 * d__1); + } + } else { + temp = z__[ii] / delta[ii]; + if (orgati) { + dpsi += temp * temp; + } else { + dphi += temp * temp; + } + c__ = w - delta[*i__] * dpsi - delta[ip1] * dphi; + } + a = (delta[*i__] + delta[ip1]) * w - delta[*i__] * delta[ip1] + * dw; + b = delta[*i__] * delta[ip1] * w; + if (c__ == 0.) { + if (a == 0.) { + if (! swtch) { + if (orgati) { + a = z__[*i__] * z__[*i__] + delta[ip1] * + delta[ip1] * (dpsi + dphi); + } else { + a = z__[ip1] * z__[ip1] + delta[*i__] * delta[ + *i__] * (dpsi + dphi); + } + } else { + a = delta[*i__] * delta[*i__] * dpsi + delta[ip1] + * delta[ip1] * dphi; + } + } + eta = b / a; + } else if (a <= 0.) { + eta = (a - sqrt((d__1 = a * a - b * 4. * c__, abs(d__1)))) + / (c__ * 2.); + } else { + eta = b * 2. / (a + sqrt((d__1 = a * a - b * 4. * c__, + abs(d__1)))); + } + } else { + +/* Interpolation using THREE most relevant poles */ + + temp = rhoinv + psi + phi; + if (swtch) { + c__ = temp - delta[iim1] * dpsi - delta[iip1] * dphi; + zz[0] = delta[iim1] * delta[iim1] * dpsi; + zz[2] = delta[iip1] * delta[iip1] * dphi; + } else { + if (orgati) { + temp1 = z__[iim1] / delta[iim1]; + temp1 *= temp1; + c__ = temp - delta[iip1] * (dpsi + dphi) - (d__[iim1] + - d__[iip1]) * temp1; + zz[0] = z__[iim1] * z__[iim1]; + zz[2] = delta[iip1] * delta[iip1] * (dpsi - temp1 + + dphi); + } else { + temp1 = z__[iip1] / delta[iip1]; + temp1 *= temp1; + c__ = temp - delta[iim1] * (dpsi + dphi) - (d__[iip1] + - d__[iim1]) * temp1; + zz[0] = delta[iim1] * delta[iim1] * (dpsi + (dphi - + temp1)); + zz[2] = z__[iip1] * z__[iip1]; + } + } + dlaed6_(&niter, &orgati, &c__, &delta[iim1], zz, &w, &eta, + info); + if (*info != 0) { + goto L250; + } + } + +/* 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.) { + eta = -w / dw; + } + temp = tau + eta; + if (temp > dltub || temp < dltlb) { + if (w < 0.) { + eta = (dltub - tau) / 2.; + } else { + eta = (dltlb - tau) / 2.; + } + } + + i__1 = *n; + for (j = 1; j <= i__1; ++j) { + delta[j] -= eta; +/* L210: */ + } + + tau += eta; + prew = w; + +/* Evaluate PSI and the derivative DPSI */ + + dpsi = 0.; + psi = 0.; + erretm = 0.; + i__1 = iim1; + for (j = 1; j <= i__1; ++j) { + temp = z__[j] / delta[j]; + psi += z__[j] * temp; + dpsi += temp * temp; + erretm += psi; +/* L220: */ + } + erretm = abs(erretm); + +/* Evaluate PHI and the derivative DPHI */ + + dphi = 0.; + phi = 0.; + i__1 = iip1; + for (j = *n; j >= i__1; --j) { + temp = z__[j] / delta[j]; + phi += z__[j] * temp; + dphi += temp * temp; + erretm += phi; +/* L230: */ + } + + temp = z__[ii] / delta[ii]; + dw = dpsi + dphi + temp * temp; + temp = z__[ii] * temp; + w = rhoinv + phi + psi + temp; + erretm = (phi - psi) * 8. + erretm + rhoinv * 2. + abs(temp) * 3. + + abs(tau) * dw; + if (w * prew > 0. && abs(w) > abs(prew) / 10.) { + swtch = ! swtch; + } + +/* L240: */ + } + +/* Return with INFO = 1, NITER = MAXIT and not converged */ + + *info = 1; + if (orgati) { + *dlam = d__[*i__] + tau; + } else { + *dlam = d__[ip1] + tau; + } + + } + +L250: + + return 0; + +/* End of DLAED4 */ + +} /* dlaed4_ */