コード例 #1
0
ファイル: main.c プロジェクト: jozzez1/Modelska
/* calculation of graph diameter */
void diameter_cal (dub * u)
{
	int k = 1, 	// maximum length in the graph
	    i, j,	// loop indices
	    cont = 0;	// continue flag for the 'do-while' loop

	gsl_matrix * M = gsl_matrix_alloc (u->N, u->N),
		   * R = gsl_matrix_alloc (u->N, u->N);

	/* we copy the matrix */
	gsl_matrix_memcpy (M, u->A);

	do
	{
		/* we scan for the zeroes, we only check the upper triangle, without diagonal */
		for (i = 0; i <= u->N - 1; i++)
		{
			cont = 0;
			for (j = i+1; j <= u->N - 1; j++)
			{
				if (!gsl_matrix_get(M, i, j))
				{
					cont = 1;
					break;
				}
			}
			if (cont) break;
		}

		if (cont)
		{
			gsl_blas_dsymm (CblasRight, CblasLower, 1.0, M, u->A, 0.0, R);
			gsl_matrix_memcpy (M, R);
			k++;
		}

		else break;

	} while (cont && k <= u->N-1);

	gsl_matrix_free (M);
	gsl_matrix_free (R);

	u->diam = k;
}
コード例 #2
0
ファイル: glm.cpp プロジェクト: rforge/mvabund
int NBinGlm::nbinfit(gsl_matrix *Y, gsl_matrix *X, gsl_matrix *O, gsl_matrix *B)
{   
    gsl_set_error_handler_off();

    initialGlm(Y, X, O, B);

    gsl_rng *rnd=gsl_rng_alloc(gsl_rng_mt19937);
    unsigned int i, j; //, isConv;
    double yij, mij, vij, hii, uij, wij, wei;
    double th, tol, dev_th_b_old;
    int status;
 //   gsl_vector_view b0j, m0j, e0j, v0j;
    gsl_matrix *WX = gsl_matrix_alloc(nRows, nParams);   
    gsl_matrix *TMP = gsl_matrix_alloc(nRows, nParams);   
    gsl_matrix *XwX = gsl_matrix_alloc(nParams, nParams);   
    gsl_vector_view Xwi, Xi, vj, dj, hj;

    for (j=0; j<nVars; j++) {  
        betaEst(j, maxiter, &tol, maxtol); //poisson
        // Get initial theta estimates
        iterconv[j]=0.0;  
        if (mmRef->estiMethod==CHI2) {
           th = getDisper(j, 1.0); 
           while ( iterconv[j]<maxiter ) {
//printf("th=%.2f, iterconv[%d]=%d\n", th, j, iterconv[j]);
               iterconv[j]++;
               dev_th_b_old = dev[j];
               betaEst(j, 1.0, &tol, th);  // 1-step beta
               th = getDisper(j, th)/th; 
               tol = ABS((dev[j]-dev_th_b_old)/(ABS(dev[j])+0.1));
               if (tol<eps) break;
         }  }
        else if (mmRef->estiMethod==NEWTON) {
            th = thetaML(0.0, j, maxiter);
            while ( iterconv[j]<maxiter ) {
               iterconv[j]++;
               dev_th_b_old = dev[j];
               th = thetaML(th, j, maxiter2);
               betaEst(j, maxiter2, &tol, th);  
               tol=ABS((dev[j]-dev_th_b_old)/(ABS(dev[j])+0.1));
               if (tol<eps) break;
        }  } 
       else {
           th = getfAfAdash(0.0, j, maxiter);
/*           lm=0;
           for (i=0; i<nRows; i++) {
               yij = gsl_matrix_get(Y, i, j);
               mij = gsl_matrix_get(Mu, i, j);
               lm = lm + llfunc( yij, mij, th);
           } */
           while ( iterconv[j]<maxiter ) {
               iterconv[j]++;
               dev_th_b_old = dev[j];
               betaEst(j, maxiter2, &tol, th);  
               th = getfAfAdash(th, j, 1.0);
               tol=ABS((dev[j]-dev_th_b_old)/(ABS(dev[j])+0.1));
               if (tol<eps) break;
           }
       }       
       if ((iterconv[j]==maxiter)&(mmRef->warning==TRUE)) 
           printf("Warning: reached maximum itrations - negative binomial may NOT converge in the %d-th variable (dev=%.4f, err=%.4f, theta=%.4f)!\n", j, dev[j], tol, th);

       // other properties based on mu and phi
       theta[j] = th;
       gsl_matrix_memcpy(WX, Xref);  
       ll[j]=0;
       for (i=0; i<nRows; i++) {
           yij = gsl_matrix_get(Y, i, j);
           mij = gsl_matrix_get(Mu, i, j);
           vij = varfunc( mij, th);
           gsl_matrix_set(Var, i, j, vij); 
           wij = sqrt(weifunc(mij, th));
           gsl_matrix_set(wHalf, i, j, wij); 
           gsl_matrix_set(Res, i, j, (yij-mij)/sqrt(vij));        
           ll[j] = ll[j] + llfunc( yij, mij, th);
           // get PIT residuals for discrete data
           wei = gsl_rng_uniform_pos (rnd); // wei ~ U(0, 1)
           uij=wei*cdf(yij, mij, th);
           if (yij>0) uij=uij+(1-wei)*cdf((yij-1),mij,th);
           gsl_matrix_set(PitRes, i, j, uij);
           // W^1/2 X
           Xwi = gsl_matrix_row (WX, i);
           gsl_vector_scale(&Xwi.vector, wij);
       }
       aic[j]=-ll[j]+2*(nParams+1);

       // X^T * W * X
       gsl_matrix_set_identity (XwX);
       gsl_blas_dsyrk (CblasLower, CblasTrans, 1.0, WX, 0.0, XwX);
       status=gsl_linalg_cholesky_decomp (XwX);
       if (status==GSL_EDOM) {
          if (mmRef->warning==TRUE)
             printf("Warning: singular matrix in calculating pit-residuals. An eps*I is added to the singular matrix.\n");
          gsl_matrix_set_identity (XwX);
          gsl_blas_dsyrk (CblasLower, CblasTrans, 1.0, WX, mintol, XwX);
          gsl_linalg_cholesky_decomp (XwX);
       }
       gsl_linalg_cholesky_invert (XwX); // (X'WX)^-1

       // Calc varBeta
       vj = gsl_matrix_column (varBeta, j);
       dj = gsl_matrix_diagonal (XwX);
       gsl_vector_memcpy (&vj.vector, &dj.vector);

       // hii is diagonal element of H=X*(X'WX)^-1*X'*W
       hj = gsl_matrix_column (sqrt1_Hii, j);
       gsl_blas_dsymm(CblasRight,CblasLower,1.0,XwX,Xref,0.0,TMP); // X*(X'WX)^-1
       for (i=0; i<nRows; i++) {
           Xwi=gsl_matrix_row(TMP, i);
           Xi=gsl_matrix_row(Xref, i);
           wij=gsl_matrix_get(wHalf, i, j);
           gsl_blas_ddot(&Xwi.vector, &Xi.vector, &hii);
           gsl_vector_set(&hj.vector, i, MAX(mintol, sqrt(MAX(0, 1-wij*wij*hii))));
//printf("hii=%.4f, wij=%.4f, sqrt(1-wij*wij*hii)=%.4f\n", hii, wij, sqrt(1-wij*wij*hii));
       }
   } // end nVar for j loop
//   gsl_matrix_div_elements (Res, sqrt1_Hii);
//   subtractMean(Res);

   gsl_matrix_free(XwX);
   gsl_matrix_free(WX);
   gsl_matrix_free(TMP);
   gsl_rng_free(rnd);

   return SUCCESS;    
}
コード例 #3
0
ファイル: glm.cpp プロジェクト: rforge/mvabund
int PoissonGlm::EstIRLS(gsl_matrix *Y, gsl_matrix *X, gsl_matrix *O, gsl_matrix *B, double *a)
{
    initialGlm(Y, X, O, B);

    gsl_set_error_handler_off();
    gsl_rng *rnd=gsl_rng_alloc(gsl_rng_mt19937);
    unsigned int i, j;   
    int status;
    double yij, mij, vij, wij, tol, hii, uij, wei;
    gsl_vector_view Xwi, Xi, vj, hj, dj;

    gsl_matrix *WX = gsl_matrix_alloc(nRows, nParams);   
    gsl_matrix *TMP = gsl_matrix_alloc(nRows, nParams);   
    gsl_matrix *XwX = gsl_matrix_alloc(nParams, nParams);   

    for (j=0; j<nVars; j++) {
       if ( a!=NULL ) theta[j]=a[j]; 
       // estimate mu and beta   
       iterconv[j] = betaEst(j, maxiter, &tol, theta[j]); 
       if ((mmRef->warning==TRUE)&(iterconv[j]==maxiter)) 
           printf("Warning: EstIRLS reached max iterations, may not converge in the %d-th variable (dev=%.4f, err=%.4f)!\n", j, dev[j], tol);
       gsl_matrix_memcpy (WX, X);
       for (i=0; i<nRows; i++) {
            mij = gsl_matrix_get(Mu, i, j);
            // get variance
            vij = varfunc( mij, theta[j] );
            gsl_matrix_set(Var, i, j, vij); 
            // get weight
            wij = sqrt(weifunc(mij, theta[j]));  
            gsl_matrix_set(wHalf, i, j, wij);             
            // get (Pearson) residuals
            yij = gsl_matrix_get(Y, i, j);
            gsl_matrix_set(Res, i, j, (yij-mij)/sqrt(vij));        
            // get PIT residuals for discrete data
            wei = gsl_rng_uniform_pos (rnd); // wei ~ U(0, 1)
            uij = wei*cdf(yij, mij, theta[j]);
            if (yij>0) uij=uij+(1-wei)*cdf((yij-1),mij,theta[j]);
            gsl_matrix_set(PitRes, i, j, uij);
            // get elementry log-likelihood    
            ll[j] = ll[j] + llfunc( yij, mij, theta[j]);
            // W^1/2 X
            Xwi = gsl_matrix_row (WX, i);
            gsl_vector_scale(&Xwi.vector, wij);            
       }      
       aic[j]=-ll[j]+2*(nParams);

       // X^T * W * X
       gsl_matrix_set_identity(XwX);
       gsl_blas_dsyrk (CblasLower, CblasTrans, 1.0, WX, 0.0, XwX);
       status=gsl_linalg_cholesky_decomp (XwX);
       if (status==GSL_EDOM) {
          if (mmRef->warning==TRUE)
             printf("Warning: singular matrix in calculating pit-residuals. An eps*I is added to the singular matrix.\n");
          gsl_matrix_set_identity(XwX);
          gsl_blas_dsyrk (CblasLower, CblasTrans, 1.0, WX, mintol, XwX);
          gsl_linalg_cholesky_decomp (XwX);
       }
       gsl_linalg_cholesky_invert (XwX);

       // Calc varBeta
       dj = gsl_matrix_diagonal (XwX);
       vj = gsl_matrix_column (varBeta, j);       
       gsl_vector_memcpy (&vj.vector, &dj.vector);

       // hii is diagonal element of H=X*(X'WX)^-1*X'*W
       hj = gsl_matrix_column (sqrt1_Hii, j);
       gsl_blas_dsymm(CblasRight,CblasLower,1.0,XwX,Xref,0.0,TMP); // X*(X'WX)^-1
       for (i=0; i<nRows; i++) {
           Xwi=gsl_matrix_row(TMP, i);
           Xi=gsl_matrix_row(Xref, i);
           wij=gsl_matrix_get(wHalf, i, j);
           gsl_blas_ddot(&Xwi.vector, &Xi.vector, &hii);
           gsl_vector_set(&hj.vector, i, MAX(mintol, sqrt(MAX(0, 1-wij*wij*hii))));
       } 
   } 
   // standardize perason residuals by rp/sqrt(1-hii) 
//   gsl_matrix_div_elements (Res, sqrt1_Hii);
//   subtractMean(Res);  // have mean subtracted

   gsl_matrix_free(XwX);
   gsl_matrix_free(WX);
   gsl_matrix_free(TMP);
   gsl_rng_free(rnd);

   return SUCCESS;    
}
コード例 #4
0
ファイル: blas.hpp プロジェクト: fujiisoup/MyLibrary
    /**
     * C++ version of gsl_blas_dsymm().
     * @param Side Side to apply operation to
     * @param Uplo Upper or lower triangular
     * @param alpha A constant
     * @param A A matrix
     * @param B Another matrix
     * @param beta Another constant
     * @param C Another matrix
     * @return Error code on failure
     */
    int dsymm( CBLAS_SIDE_t Side, CBLAS_UPLO_t Uplo, double alpha,
	       matrix const& A, matrix const& B, double beta, matrix& C ){
      return gsl_blas_dsymm( Side, Uplo, alpha, A.get(), B.get(), beta, C.get() ); }
コード例 #5
0
ファイル: Matrix.c プロジェクト: rishabhy/Cscience
int MatMulSym(Matrix &C, Matrix &A, Matrix &B) {

    return gsl_blas_dsymm( CblasLeft, CblasUpper, 1.0, A.Ma(), B.Ma(), 0.0, C.Ma());
}
コード例 #6
0
ファイル: LatticeTilingTest.c プロジェクト: spxiwh/lalsuite
static int MismatchTest(
  LatticeTiling *tiling,
  gsl_matrix *metric,
  const double max_mismatch,
  const UINT8 total_ref,
  const double mism_hist_ref[MISM_HIST_BINS]
  )
{

  const size_t n = XLALTotalLatticeTilingDimensions(tiling);

  // Create lattice tiling iterator and locator
  LatticeTilingIterator *itr = XLALCreateLatticeTilingIterator(tiling, n);
  XLAL_CHECK(itr != NULL, XLAL_EFUNC);
  LatticeTilingLocator *loc = XLALCreateLatticeTilingLocator(tiling);
  XLAL_CHECK(loc != NULL, XLAL_EFUNC);

  // Count number of points
  const UINT8 total = XLALTotalLatticeTilingPoints(itr);
  printf("Number of lattice points: %" LAL_UINT8_FORMAT "\n", total);
  XLAL_CHECK(imaxabs(total - total_ref) <= 1, XLAL_EFUNC, "ERROR: |total - total_ref| = |%" LAL_UINT8_FORMAT " - %" LAL_UINT8_FORMAT "| > 1", total, total_ref);

  // Get all points
  gsl_matrix *GAMAT(points, n, total);
  XLAL_CHECK(XLALNextLatticeTilingPoints(itr, &points) == (int)total, XLAL_EFUNC);
  XLAL_CHECK(XLALNextLatticeTilingPoint(itr, NULL) == 0, XLAL_EFUNC);

  // Initialise mismatch histogram counts
  double mism_hist[MISM_HIST_BINS] = {0};
  double mism_hist_total = 0, mism_hist_out_of_range = 0;

  // Perform 10 injections for every template
  {
    gsl_matrix *GAMAT(injections, 3, total);
    gsl_matrix *GAMAT(nearest, 3, total);
    gsl_matrix *GAMAT(temp, 3, total);
    RandomParams *rng = XLALCreateRandomParams(total);
    XLAL_CHECK(rng != NULL, XLAL_EFUNC);
    for (size_t i = 0; i < 10; ++i) {

      // Generate random injection points
      XLAL_CHECK(XLALRandomLatticeTilingPoints(tiling, 0.0, rng, injections) == XLAL_SUCCESS, XLAL_EFUNC);

      // Find nearest lattice template points
      XLAL_CHECK(XLALNearestLatticeTilingPoints(loc, injections, &nearest, NULL) == XLAL_SUCCESS, XLAL_EFUNC);

      // Compute mismatch between injections
      gsl_matrix_sub(nearest, injections);
      gsl_blas_dsymm(CblasLeft, CblasUpper, 1.0, metric, nearest, 0.0, temp);
      for (size_t j = 0; j < temp->size2; ++j) {
        gsl_vector_view temp_j = gsl_matrix_column(temp, j);
        gsl_vector_view nearest_j = gsl_matrix_column(nearest, j);
        double mismatch = 0.0;
        gsl_blas_ddot(&nearest_j.vector, &temp_j.vector, &mismatch);
        mismatch /= max_mismatch;

        // Increment mismatch histogram counts
        ++mism_hist_total;
        if (mismatch < 0.0 || mismatch > 1.0) {
          ++mism_hist_out_of_range;
        } else {
          ++mism_hist[lround(floor(mismatch * MISM_HIST_BINS))];
        }

      }

    }

    // Cleanup
    GFMAT(injections, nearest, temp);
    XLALDestroyRandomParams(rng);

  }

  // Normalise histogram
  for (size_t i = 0; i < MISM_HIST_BINS; ++i) {
    mism_hist[i] *= MISM_HIST_BINS / mism_hist_total;
  }

  // Print mismatch histogram and its reference
  printf("Mismatch histogram: ");
  for (size_t i = 0; i < MISM_HIST_BINS; ++i) {
    printf(" %0.3f", mism_hist[i]);
  }
  printf("\n");
  printf("Reference histogram:");
  for (size_t i = 0; i < MISM_HIST_BINS; ++i) {
    printf(" %0.3f", mism_hist_ref[i]);
  }
  printf("\n");

  // Determine error between mismatch histogram and its reference
  double mism_hist_error = 0.0;
  for (size_t i = 0; i < MISM_HIST_BINS; ++i) {
    mism_hist_error += fabs(mism_hist[i] - mism_hist_ref[i]);
  }
  mism_hist_error /= MISM_HIST_BINS;
  printf("Mismatch histogram error: %0.3e\n", mism_hist_error);
  const double mism_hist_error_tol = 5e-2;
  if (mism_hist_error >= mism_hist_error_tol) {
    XLAL_ERROR(XLAL_EFAILED, "ERROR: mismatch histogram error exceeds %0.3e\n", mism_hist_error_tol);
  }

  // Check fraction of injections out of histogram range
  const double mism_out_of_range = mism_hist_out_of_range / mism_hist_total;
  printf("Fraction of points out of histogram range: %0.3e\n", mism_out_of_range);
  const double mism_out_of_range_tol = 2e-3;
  if (mism_out_of_range > mism_out_of_range_tol) {
    XLAL_ERROR(XLAL_EFAILED, "ERROR: fraction of points out of histogram range exceeds %0.3e\n", mism_out_of_range_tol);
  }

  // Perform 10 injections outside parameter space
  {
    gsl_matrix *GAMAT(injections, 3, 10);
    gsl_matrix *GAMAT(nearest, n, total);
    RandomParams *rng = XLALCreateRandomParams(total);
    XLAL_CHECK(rng != NULL, XLAL_EFUNC);

    // Generate random injection points outside parameter space
    XLAL_CHECK(XLALRandomLatticeTilingPoints(tiling, 5.0, rng, injections) == XLAL_SUCCESS, XLAL_EFUNC);

    // Find nearest lattice template points
    XLAL_CHECK(XLALNearestLatticeTilingPoints(loc, injections, &nearest, NULL) == XLAL_SUCCESS, XLAL_EFUNC);

    // Cleanup
    GFMAT(injections, nearest);
    XLALDestroyRandomParams(rng);

  }

  // Cleanup
  XLALDestroyLatticeTiling(tiling);
  XLALDestroyLatticeTilingIterator(itr);
  XLALDestroyLatticeTilingLocator(loc);
  GFMAT(metric, points);
  LALCheckMemoryLeaks();
  printf("\n");
  fflush(stdout);

  return XLAL_SUCCESS;

}
コード例 #7
0
ファイル: blas3.c プロジェクト: rbalint/rb-gsl
static VALUE rb_gsl_blas_dsymm(int argc, VALUE *argv, VALUE obj)
{
  gsl_matrix *A = NULL, *B = NULL, *C = NULL;
  double alpha, beta;
  CBLAS_SIDE_t Side;
  CBLAS_UPLO_t Uplo;
  int flag = 0;
  switch (argc) {
  case 2:
    CHECK_MATRIX(argv[0]);
    CHECK_MATRIX(argv[1]);
    Data_Get_Struct(argv[0], gsl_matrix, A);
    Data_Get_Struct(argv[1], gsl_matrix, B);
    C = gsl_matrix_calloc(A->size1, B->size2);
    alpha = 1.0;
    beta = 0.0;
    Side = CblasLeft;  Uplo = CblasUpper;
    flag = 1;
    break;
  case 5:
    CHECK_FIXNUM(argv[0]);
    CHECK_FIXNUM(argv[1]);
    Need_Float(argv[2]);
    CHECK_MATRIX(argv[3]);
    CHECK_MATRIX(argv[4]);
    Side = FIX2INT(argv[0]);
    Uplo = FIX2INT(argv[1]);
    alpha = NUM2DBL(argv[2]);
    Data_Get_Struct(argv[3], gsl_matrix, A);
    Data_Get_Struct(argv[4], gsl_matrix, B);
    C = gsl_matrix_calloc(A->size1, B->size2);
    beta = 0.0;
    flag = 1;
    break;
  case 6:
    CHECK_FIXNUM(argv[0]);
    CHECK_FIXNUM(argv[1]);
    Need_Float(argv[2]);
    CHECK_MATRIX(argv[3]);
    CHECK_MATRIX(argv[4]);
    Need_Float(argv[5]);
    CHECK_MATRIX(argv[6]);
    Side = FIX2INT(argv[0]);
    Uplo = FIX2INT(argv[1]);
    alpha = NUM2DBL(argv[2]);
    Data_Get_Struct(argv[3], gsl_matrix, A);
    Data_Get_Struct(argv[4], gsl_matrix, B);
    beta = NUM2DBL(argv[5]);
    C = gsl_matrix_calloc(A->size1, B->size2);
    flag = 1;
    break;
  case 7:
    CHECK_FIXNUM(argv[0]);
    CHECK_FIXNUM(argv[1]);
    Need_Float(argv[2]);
    CHECK_MATRIX(argv[3]);
    CHECK_MATRIX(argv[4]);
    Need_Float(argv[5]);
    CHECK_MATRIX(argv[6]);
    Side = FIX2INT(argv[0]);
    Uplo = FIX2INT(argv[1]);
    alpha = NUM2DBL(argv[2]);
    Data_Get_Struct(argv[3], gsl_matrix, A);
    Data_Get_Struct(argv[4], gsl_matrix, B);
    beta = NUM2DBL(argv[5]);
    Data_Get_Struct(argv[6], gsl_matrix, C);
    break;
  default:
    rb_raise(rb_eArgError, "wrong number of arguments (%d for 2 or 7)", argc);
    break;
  }
  gsl_blas_dsymm(Side, Uplo, alpha, A, B, beta, C);
  if (flag == 1) return Data_Wrap_Struct(cgsl_matrix, 0, gsl_matrix_free, C);
  else return argv[6];
}
コード例 #8
0
ファイル: linreg.c プロジェクト: RobertDash/pspp
static void
post_sweep_computations (linreg *l, gsl_matrix *sw)
{
  gsl_matrix *xm;
  gsl_matrix_view xtx;
  gsl_matrix_view xmxtx;
  double m;
  double tmp;
  size_t i;
  size_t j;
  int rc;
  
  assert (sw != NULL);
  assert (l != NULL);

  l->sse = gsl_matrix_get (sw, l->n_indeps, l->n_indeps);
  l->mse = l->sse / l->dfe;
  /*
    Get the intercept.
  */
  m = l->depvar_mean;
  for (i = 0; i < l->n_indeps; i++)
    {
      tmp = gsl_matrix_get (sw, i, l->n_indeps);
      l->coeff[i] = tmp;
      m -= tmp * linreg_get_indep_variable_mean (l, i);
    }
  /*
    Get the covariance matrix of the parameter estimates.
    Only the upper triangle is necessary.
  */
  
  /*
    The loops below do not compute the entries related
    to the estimated intercept.
  */
  for (i = 0; i < l->n_indeps; i++)
    for (j = i; j < l->n_indeps; j++)
      {
	tmp = -1.0 * l->mse * gsl_matrix_get (sw, i, j);
	gsl_matrix_set (l->cov, i + 1, j + 1, tmp);
      }
  /*
    Get the covariances related to the intercept.
  */
  xtx = gsl_matrix_submatrix (sw, 0, 0, l->n_indeps, l->n_indeps);
  xmxtx = gsl_matrix_submatrix (l->cov, 0, 1, 1, l->n_indeps);
  xm = gsl_matrix_calloc (1, l->n_indeps);
  for (i = 0; i < xm->size2; i++)
    {
      gsl_matrix_set (xm, 0, i, 
		      linreg_get_indep_variable_mean (l, i));
    }
  rc = gsl_blas_dsymm (CblasRight, CblasUpper, l->mse,
		       &xtx.matrix, xm, 0.0, &xmxtx.matrix);
  gsl_matrix_free (xm);
  if (rc == GSL_SUCCESS)
    {
      tmp = l->mse / l->n_obs;
      for (i = 1; i < 1 + l->n_indeps; i++)
	{
	  tmp -= gsl_matrix_get (l->cov, 0, i)
	    * linreg_get_indep_variable_mean (l, i - 1);
	}
      gsl_matrix_set (l->cov, 0, 0, tmp);
      
      l->intercept = m;
    }
  else
    {
      fprintf (stderr, "%s:%d:gsl_blas_dsymm: %s\n",
	       __FILE__, __LINE__, gsl_strerror (rc));
      exit (rc);
    }
}