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#include "nnls.h"

/*
  NNLS-Chroma / Chordino

  This file is converted from the Netlib FORTRAN code NNLS.FOR,
  developed by Charles L. Lawson and Richard J. Hanson at Jet
  Propulsion Laboratory 1973 JUN 15, and published in the book
  "SOLVING LEAST SQUARES PROBLEMS", Prentice-Hall, 1974.

  Refer to nnls.f for the original code and comments.
*/

#include <math.h>

#define nnls_max(a,b) ((a) >= (b) ? (a) : (b))
#define nnls_abs(x) ((x) >= 0 ? (x) : -(x))

float d_sign(float a, float b)
{
  float x;
  x = (a >= 0 ? a : - a);
  return (b >= 0 ? x : -x);
}

/* Table of constant values */

int c__1 = 1;
int c__0 = 0;
int c__2 = 2;


int g1(float* a, float* b, float* cterm, float* sterm, float* sig)
{
  /* System generated locals */
  float d;

  float xr, yr;


  if (nnls_abs(*a) > nnls_abs(*b)) {
    xr = *b / *a;
    /* Computing 2nd power */
    d = xr;
    yr = sqrt(d * d + 1.);
    d = 1. / yr;
    *cterm = d_sign(d, *a);
    *sterm = *cterm * xr;
    *sig = nnls_abs(*a) * yr;
    return 0;
  }
  if (*b != 0.) {
    xr = *a / *b;
    /* Computing 2nd power */
    d = xr;
    yr = sqrt(d * d + 1.);
    d = 1. / yr;
    *sterm = d_sign(d, *b);
    *cterm = *sterm * xr;
    *sig = nnls_abs(*b) * yr;
    return 0;
  }
  *sig = 0.;
  *cterm = 0.;
  *sterm = 1.;
  return 0;
} /* g1_ */

int h12(int mode, int* lpivot, int* l1,
        int m, float* u, int* iue, float* up, float* c__,
        int* ice, int* icv, int* ncv)
{
  /* System generated locals */
  int u_dim1, u_offset, idx1, idx2;
  float d, d2;

  /* Local variables */
  int incr;
  float b;
  int i__, j;
  float clinv;
  int i2, i3, i4;
  float cl, sm;

  /*     ------------------------------------------------------------------
   */
  /*     float precision U(IUE,M) */
  /*     ------------------------------------------------------------------
   */
  /* Parameter adjustments */
  u_dim1 = *iue;
  u_offset = u_dim1 + 1;
  u -= u_offset;
  --c__;

  /* Function Body */
  if (0 >= *lpivot || *lpivot >= *l1 || *l1 > m) {
    return 0;
  }
  cl = (d = u[*lpivot * u_dim1 + 1], nnls_abs(d));
  if (mode == 2) {
    goto L60;
  }
  /*                            ****** CONSTRUCT THE TRANSFORMATION. ******
   */
  idx1 = m;
  for (j = *l1; j <= idx1; ++j) {
    /* L10: */
    /* Computing MAX */
    d2 = (d = u[j * u_dim1 + 1], nnls_abs(d));
    cl = nnls_max(d2,cl);
  }
  if (cl <= 0.) {
    goto L130;
  } else {
    goto L20;
  }
 L20:
  clinv = 1. / cl;
  /* Computing 2nd power */
  d = u[*lpivot * u_dim1 + 1] * clinv;
  sm = d * d;
  idx1 = m;
  for (j = *l1; j <= idx1; ++j) {
    /* L30: */
    /* Computing 2nd power */
    d = u[j * u_dim1 + 1] * clinv;
    sm += d * d;
  }
  cl *= sqrt(sm);
  if (u[*lpivot * u_dim1 + 1] <= 0.) {
    goto L50;
  } else {
    goto L40;
  }
 L40:
  cl = -cl;
 L50:
  *up = u[*lpivot * u_dim1 + 1] - cl;
  u[*lpivot * u_dim1 + 1] = cl;
  goto L70;
  /*            ****** APPLY THE TRANSFORMATION  I+U*(U**T)/B  TO C. ******
   */

 L60:
  if (cl <= 0.) {
    goto L130;
  } else {
    goto L70;
  }
 L70:
  if (*ncv <= 0) {
    return 0;
  }
  b = *up * u[*lpivot * u_dim1 + 1];
  /*                       B  MUST BE NONPOSITIVE HERE.  IF B = 0., RETURN.
   */

  if (b >= 0.) {
    goto L130;
  } else {
    goto L80;
  }
 L80:
  b = 1. / b;
  i2 = 1 - *icv + *ice * (*lpivot - 1);
  incr = *ice * (*l1 - *lpivot);
  idx1 = *ncv;
  for (j = 1; j <= idx1; ++j) {
    i2 += *icv;
    i3 = i2 + incr;
    i4 = i3;
    sm = c__[i2] * *up;
    idx2 = m;
    for (i__ = *l1; i__ <= idx2; ++i__) {
      sm += c__[i3] * u[i__ * u_dim1 + 1];
      /* L90: */
      i3 += *ice;
    }
    if (sm != 0.) {
      goto L100;
    } else {
      goto L120;
    }
  L100:
    sm *= b;
    c__[i2] += sm * *up;
    idx2 = m;
    for (i__ = *l1; i__ <= idx2; ++i__) {
      c__[i4] += sm * u[i__ * u_dim1 + 1];
      /* L110: */
      i4 += *ice;
    }
  L120:
    ;
  }
 L130:
  return 0;
} /* h12 */

int nnls(float* a,  int mda,  int m,  int n, float* b,
         float* x, float* rnorm, float* w, float* zz, int* index,
         int* mode)
{
  /* System generated locals */
  int a_dim1, a_offset, idx1, idx2;
  float d1, d2;


  /* Local variables */
  int iter;
  float temp, wmax;
  int i__, j, l;
  float t, alpha, asave;
  int itmax, izmax = 0, nsetp;
  float unorm, ztest, cc;
  float dummy[2];
  int ii, jj, ip;
  float sm;
  int iz, jz;
  float up, ss;
  int rtnkey, iz1, iz2, npp1;

  /*     ------------------------------------------------------------------
   */
  /*     int INDEX(N) */
  /*     float precision A(MDA,N), B(M), W(N), X(N), ZZ(M) */
  /*     ------------------------------------------------------------------
   */
  /* Parameter adjustments */
  a_dim1 = mda;
  a_offset = a_dim1 + 1;
  a -= a_offset;
  --b;
  --x;
  --w;
  --zz;
  --index;

  /* Function Body */
  *mode = 1;
  if (m <= 0 || n <= 0) {
    *mode = 2;
    return 0;
  }
  iter = 0;
  itmax = n * 3;

  /*                    INITIALIZE THE ARRAYS INDEX() AND X(). */

  idx1 = n;
  for (i__ = 1; i__ <= idx1; ++i__) {
    x[i__] = 0.;
    /* L20: */
    index[i__] = i__;
  }

  iz2 = n;
  iz1 = 1;
  nsetp = 0;
  npp1 = 1;
  /*                             ******  MAIN LOOP BEGINS HERE  ****** */
 L30:
  /*                  QUIT IF ALL COEFFICIENTS ARE ALREADY IN THE SOLUTION.
   */
  /*                        OR IF M COLS OF A HAVE BEEN TRIANGULARIZED. */

  if (iz1 > iz2 || nsetp >= m) {
    goto L350;
  }

  /*         COMPUTE COMPONENTS OF THE DUAL (NEGATIVE GRADIENT) VECTOR W().
   */

  idx1 = iz2;
  for (iz = iz1; iz <= idx1; ++iz) {
    j = index[iz];
    sm = 0.;
    idx2 = m;
    for (l = npp1; l <= idx2; ++l) {
      /* L40: */
      sm += a[l + j * a_dim1] * b[l];
    }
    w[j] = sm;
    /* L50: */
  }
  /*                                   FIND LARGEST POSITIVE W(J). */
 L60:
  wmax = 0.;
  idx1 = iz2;
  for (iz = iz1; iz <= idx1; ++iz) {
    j = index[iz];
    if (w[j] > wmax) {
      wmax = w[j];
      izmax = iz;
    }
    /* L70: */
  }

  /*             IF WMAX .LE. 0. GO TO TERMINATION. */
  /*             THIS INDICATES SATISFACTION OF THE KUHN-TUCKER CONDITIONS.
   */

  if (wmax <= 0.) {
    goto L350;
  }
  iz = izmax;
  j = index[iz];

  /*     THE SIGN OF W(J) IS OK FOR J TO BE MOVED TO SET P. */
  /*     BEGIN THE TRANSFORMATION AND CHECK NEW DIAGONAL ELEMENT TO AVOID */
  /*     NEAR LINEAR DEPENDENCE. */

  asave = a[npp1 + j * a_dim1];
  idx1 = npp1 + 1;
  h12(c__1, &npp1, &idx1, m, &a[j * a_dim1 + 1], &c__1, &up, dummy, &
      c__1, &c__1, &c__0);
  unorm = 0.;
  if (nsetp != 0) {
    idx1 = nsetp;
    for (l = 1; l <= idx1; ++l) {
      /* L90: */
      /* Computing 2nd power */
      d1 = a[l + j * a_dim1];
      unorm += d1 * d1;
    }
  }
  unorm = sqrt(unorm);
  d2 = unorm + (d1 = a[npp1 + j * a_dim1], nnls_abs(d1)) * .01;
  if ((d2- unorm) > 0.) {

    /*        COL J IS SUFFICIENTLY INDEPENDENT.  COPY B INTO ZZ, UPDATE Z
              Z */
    /*        AND SOLVE FOR ZTEST ( = PROPOSED NEW VALUE FOR X(J) ). */

    idx1 = m;
    for (l = 1; l <= idx1; ++l) {
      /* L120: */
      zz[l] = b[l];
    }
    idx1 = npp1 + 1;
    h12(c__2, &npp1, &idx1, m, &a[j * a_dim1 + 1], &c__1, &up, (zz+1), &
        c__1, &c__1, &c__1);
    ztest = zz[npp1] / a[npp1 + j * a_dim1];

    /*                                     SEE IF ZTEST IS POSITIVE */

    if (ztest > 0.) {
      goto L140;
    }
  }

  /*     REJECT J AS A CANDIDATE TO BE MOVED FROM SET Z TO SET P. */
  /*     RESTORE A(NPP1,J), SET W(J)=0., AND LOOP BACK TO TEST DUAL */
  /*     COEFFS AGAIN. */

  a[npp1 + j * a_dim1] = asave;
  w[j] = 0.;
  goto L60;

  /*     THE INDEX  J=INDEX(IZ)  HAS BEEN SELECTED TO BE MOVED FROM */
  /*     SET Z TO SET P.    UPDATE B,  UPDATE INDICES,  APPLY HOUSEHOLDER */
  /*     TRANSFORMATIONS TO COLS IN NEW SET Z,  ZERO SUBDIAGONAL ELTS IN */
  /*     COL J,  SET W(J)=0. */

 L140:
  idx1 = m;
  for (l = 1; l <= idx1; ++l) {
    /* L150: */
    b[l] = zz[l];
  }

  index[iz] = index[iz1];
  index[iz1] = j;
  ++iz1;
  nsetp = npp1;
  ++npp1;

  if (iz1 <= iz2) {
    idx1 = iz2;
    for (jz = iz1; jz <= idx1; ++jz) {
      jj = index[jz];
      h12(c__2, &nsetp, &npp1, m,
          &a[j * a_dim1 + 1], &c__1, &up,
          &a[jj * a_dim1 + 1], &c__1, &mda, &c__1);
      /* L160: */
    }
  }

  if (nsetp != m) {
    idx1 = m;
    for (l = npp1; l <= idx1; ++l) {
      /* L180: */
      // SS: CHECK THIS DAMAGE....
      a[l + j * a_dim1] = 0.;
    }
  }

  w[j] = 0.;
  /*                                SOLVE THE TRIANGULAR SYSTEM. */
  /*                                STORE THE SOLUTION TEMPORARILY IN ZZ().
   */
  rtnkey = 1;
  goto L400;
 L200:

  /*                       ******  SECONDARY LOOP BEGINS HERE ****** */

  /*                          ITERATION COUNTER. */

 L210:
  ++iter;
  if (iter > itmax) {
    *mode = 3;
    goto L350;
  }

  /*                    SEE IF ALL NEW CONSTRAINED COEFFS ARE FEASIBLE. */
  /*                                  IF NOT COMPUTE ALPHA. */

  alpha = 2.;
  idx1 = nsetp;
  for (ip = 1; ip <= idx1; ++ip) {
    l = index[ip];
    if (zz[ip] <= 0.) {
      t = -x[l] / (zz[ip] - x[l]);
      if (alpha > t) {
        alpha = t;
        jj = ip;
      }
    }
    /* L240: */
  }

  /*          IF ALL NEW CONSTRAINED COEFFS ARE FEASIBLE THEN ALPHA WILL */
  /*          STILL = 2.    IF SO EXIT FROM SECONDARY LOOP TO MAIN LOOP. */

  if (alpha == 2.) {
    goto L330;
  }

  /*          OTHERWISE USE ALPHA WHICH WILL BE BETWEEN 0. AND 1. TO */
  /*          INTERPOLATE BETWEEN THE OLD X AND THE NEW ZZ. */

  idx1 = nsetp;
  for (ip = 1; ip <= idx1; ++ip) {
    l = index[ip];
    x[l] += alpha * (zz[ip] - x[l]);
    /* L250: */
  }

  /*        MODIFY A AND B AND THE INDEX ARRAYS TO MOVE COEFFICIENT I */
  /*        FROM SET P TO SET Z. */

  i__ = index[jj];
 L260:
  x[i__] = 0.;

  if (jj != nsetp) {
    ++jj;
    idx1 = nsetp;
    for (j = jj; j <= idx1; ++j) {
      ii = index[j];
      index[j - 1] = ii;
      g1(&a[j - 1 + ii * a_dim1], &a[j + ii * a_dim1],
         &cc, &ss, &a[j - 1 + ii * a_dim1]);
      // SS: CHECK THIS DAMAGE...
      a[j + ii * a_dim1] = 0.;
      idx2 = n;
      for (l = 1; l <= idx2; ++l) {
        if (l != ii) {

          /*                 Apply procedure G2 (CC,SS,A(J-1,L),A(J,
                             L)) */

          temp = a[j - 1 + l * a_dim1];
          // SS: CHECK THIS DAMAGE
          a[j - 1 + l * a_dim1] = cc * temp + ss * a[j + l * a_dim1];
          a[j + l * a_dim1] = -ss * temp + cc * a[j + l * a_dim1];
        }
        /* L270: */
      }

      /*                 Apply procedure G2 (CC,SS,B(J-1),B(J)) */

      temp = b[j - 1];
      b[j - 1] = cc * temp + ss * b[j];
      b[j] = -ss * temp + cc * b[j];
      /* L280: */
    }
  }

  npp1 = nsetp;
  --nsetp;
  --iz1;
  index[iz1] = i__;

  /*        SEE IF THE REMAINING COEFFS IN SET P ARE FEASIBLE.  THEY SHOULD
   */
  /*        BE BECAUSE OF THE WAY ALPHA WAS DETERMINED. */
  /*        IF ANY ARE INFEASIBLE IT IS DUE TO ROUND-OFF ERROR.  ANY */
  /*        THAT ARE NONPOSITIVE WILL BE SET TO ZERO */
  /*        AND MOVED FROM SET P TO SET Z. */

  idx1 = nsetp;
  for (jj = 1; jj <= idx1; ++jj) {
    i__ = index[jj];
    if (x[i__] <= 0.) {
      goto L260;
    }
    /* L300: */
  }

  /*         COPY B( ) INTO ZZ( ).  THEN SOLVE AGAIN AND LOOP BACK. */

  idx1 = m;
  for (i__ = 1; i__ <= idx1; ++i__) {
    /* L310: */
    zz[i__] = b[i__];
  }
  rtnkey = 2;
  goto L400;
 L320:
  goto L210;
  /*                      ******  END OF SECONDARY LOOP  ****** */

 L330:
  idx1 = nsetp;
  for (ip = 1; ip <= idx1; ++ip) {
    i__ = index[ip];
    /* L340: */
    x[i__] = zz[ip];
  }
  /*        ALL NEW COEFFS ARE POSITIVE.  LOOP BACK TO BEGINNING. */
  goto L30;

  /*                        ******  END OF MAIN LOOP  ****** */

  /*                        COME TO HERE FOR TERMINATION. */
  /*                     COMPUTE THE NORM OF THE FINAL RESIDUAL VECTOR. */

 L350:
  sm = 0.;
  if (npp1 <= m) {
    idx1 = m;
    for (i__ = npp1; i__ <= idx1; ++i__) {
      /* L360: */
      /* Computing 2nd power */
      d1 = b[i__];
      sm += d1 * d1;
    }
  } else {
    idx1 = n;
    for (j = 1; j <= idx1; ++j) {
      /* L380: */
      w[j] = 0.;
    }
  }
  *rnorm = sqrt(sm);
  return 0;

  /*     THE FOLLOWING BLOCK OF CODE IS USED AS AN INTERNAL SUBROUTINE */
  /*     TO SOLVE THE TRIANGULAR SYSTEM, PUTTING THE SOLUTION IN ZZ(). */

 L400:
  idx1 = nsetp;
  for (l = 1; l <= idx1; ++l) {
    ip = nsetp + 1 - l;
    if (l != 1) {
      idx2 = ip;
      for (ii = 1; ii <= idx2; ++ii) {
        zz[ii] -= a[ii + jj * a_dim1] * zz[ip + 1];
        /* L410: */
      }
    }
    jj = index[ip];
    zz[ip] /= a[ip + jj * a_dim1];
    /* L430: */
  }
  switch ((int)rtnkey) {
  case 1:  goto L200;
  case 2:  goto L320;
  }

  return 0;

} /* nnls_ */