# include # include # include # include # include "r8utt.h" /******************************************************************************/ int i4_log_10 ( int i ) /******************************************************************************/ /* Purpose: I4_LOG_10 returns the integer part of the logarithm base 10 of an I4. Example: I I4_LOG_10 ----- -------- 0 0 1 0 2 0 9 0 10 1 11 1 99 1 100 2 101 2 999 2 1000 3 1001 3 9999 3 10000 4 Discussion: I4_LOG_10 ( I ) + 1 is the number of decimal digits in I. Licensing: This code is distributed under the MIT license. Modified: 23 October 2007 Author: John Burkardt Parameters: Input, int I, the number whose logarithm base 10 is desired. Output, int I4_LOG_10, the integer part of the logarithm base 10 of the absolute value of X. */ { int i_abs; int ten_pow; int value; if ( i == 0 ) { value = 0; } else { value = 0; ten_pow = 10; i_abs = abs ( i ); while ( ten_pow <= i_abs ) { value = value + 1; ten_pow = ten_pow * 10; } } return value; } /******************************************************************************/ int i4_max ( int i1, int i2 ) /******************************************************************************/ /* Purpose: I4_MAX returns the maximum of two I4's. Licensing: This code is distributed under the MIT license. Modified: 29 August 2006 Author: John Burkardt Parameters: Input, int I1, I2, are two integers to be compared. Output, int I4_MAX, the larger of I1 and I2. */ { int value; if ( i2 < i1 ) { value = i1; } else { value = i2; } return value; } /******************************************************************************/ int i4_min ( int i1, int i2 ) /******************************************************************************/ /* Purpose: I4_MIN returns the smaller of two I4's. Licensing: This code is distributed under the MIT license. Modified: 29 August 2006 Author: John Burkardt Parameters: Input, int I1, I2, two integers to be compared. Output, int I4_MIN, the smaller of I1 and I2. */ { int value; if ( i1 < i2 ) { value = i1; } else { value = i2; } return value; } /******************************************************************************/ int i4_power ( int i, int j ) /******************************************************************************/ /* Purpose: I4_POWER returns the value of I^J. Licensing: This code is distributed under the MIT license. Modified: 23 October 2007 Author: John Burkardt Parameters: Input, int I, J, the base and the power. J should be nonnegative. Output, int I4_POWER, the value of I^J. */ { int k; int value; if ( j < 0 ) { if ( i == 1 ) { value = 1; } else if ( i == 0 ) { fprintf ( stderr, "\n" ); fprintf ( stderr, "I4_POWER - Fatal error!\n" ); fprintf ( stderr, " I^J requested, with I = 0 and J negative.\n" ); exit ( 1 ); } else { value = 0; } } else if ( j == 0 ) { if ( i == 0 ) { fprintf ( stderr, "\n" ); fprintf ( stderr, "I4_POWER - Fatal error!\n" ); fprintf ( stderr, " I^J requested, with I = 0 and J = 0.\n" ); exit ( 1 ); } else { value = 1; } } else if ( j == 1 ) { value = i; } else { value = 1; for ( k = 1; k <= j; k++ ) { value = value * i; } } return value; } /******************************************************************************/ double r8_uniform_01 ( int *seed ) /******************************************************************************/ /* Purpose: R8_UNIFORM_01 returns a unit pseudorandom R8. Discussion: This routine implements the recursion seed = 16807 * seed mod ( 2^31 - 1 ) r8_uniform_01 = seed / ( 2^31 - 1 ) The integer arithmetic never requires more than 32 bits, including a sign bit. If the initial seed is 12345, then the first three computations are Input Output R8_UNIFORM_01 SEED SEED 12345 207482415 0.096616 207482415 1790989824 0.833995 1790989824 2035175616 0.947702 Licensing: This code is distributed under the MIT license. Modified: 11 August 2004 Author: John Burkardt Reference: Paul Bratley, Bennett Fox, Linus Schrage, A Guide to Simulation, Springer Verlag, pages 201-202, 1983. Pierre L'Ecuyer, Random Number Generation, in Handbook of Simulation edited by Jerry Banks, Wiley Interscience, page 95, 1998. Bennett Fox, Algorithm 647: Implementation and Relative Efficiency of Quasirandom Sequence Generators, ACM Transactions on Mathematical Software, Volume 12, Number 4, pages 362-376, 1986. P A Lewis, A S Goodman, J M Miller, A Pseudo-Random Number Generator for the System/360, IBM Systems Journal, Volume 8, pages 136-143, 1969. Parameters: Input/output, int *SEED, the "seed" value. Normally, this value should not be 0. On output, SEED has been updated. Output, double R8_UNIFORM_01, a new pseudorandom variate, strictly between 0 and 1. */ { int k; double r; k = *seed / 127773; *seed = 16807 * ( *seed - k * 127773 ) - k * 2836; if ( *seed < 0 ) { *seed = *seed + 2147483647; } /* Although SEED can be represented exactly as a 32 bit integer, it generally cannot be represented exactly as a 32 bit real number! */ r = ( ( double ) ( *seed ) ) * 4.656612875E-10; return r; } /******************************************************************************/ double *r8ge_mm ( int n, double a[], double b[] ) /******************************************************************************/ /* Purpose: R8GE_MM multiplies two R8GE matrices. Discussion: The R8GE storage format is used for a "general" M by N matrix. A physical storage space is made for each logical entry. The two dimensional logical array is mapped to a vector, in which storage is by columns. Licensing: This code is distributed under the MIT license. Modified: 28 February 2012 Author: John Burkardt Parameters: Input, int N, the order of the matrices. N must be positive. Input, double A[N*N], B[N*N], the factors. Output, double C[N*N], the product. */ { double *c; int i; int j; int k; c = ( double * ) malloc ( n * n * sizeof ( double ) ); for ( j = 0; j < n; j++ ) { for ( i = 0; i < n; i++ ) { c[i+j*n] = 0.0; for ( k = 0; k < n; k++ ) { c[i+j*n] = c[i+j*n] + a[i+k*n] * b[k+j*n]; } } } return c; } /******************************************************************************/ double *r8ge_mtm ( int n, double a[], double b[] ) /******************************************************************************/ /* Purpose: R8GE_MTM computes C=A'*B for R8GE matrices. Discussion: The R8GE storage format is used for a "general" M by N matrix. A physical storage space is made for each logical entry. The two dimensional logical array is mapped to a vector, in which storage is by columns. Licensing: This code is distributed under the MIT license. Modified: 04 August 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrices. N must be positive. Input, double A[N*N], B[N*N], the factors. Output, double C[N*N], the product. */ { double *c; int i; int j; int k; c = ( double * ) malloc ( n * n * sizeof ( double ) ); for ( j = 0; j < n; j++ ) { for ( i = 0; i < n; i++ ) { c[i+j*n] = 0.0; for ( k = 0; k < n; k++ ) { c[i+j*n] = c[i+j*n] + a[k+i*n] * b[k+j*n]; } } } return c; } /******************************************************************************/ void r8ge_print ( int m, int n, double a[], char *title ) /******************************************************************************/ /* Purpose: R8GE_PRINT prints an R8GE matrix. Discussion: The R8GE storage format is used for a "general" M by N matrix. A physical storage space is made for each logical entry. The two dimensional logical array is mapped to a vector, in which storage is by columns. Licensing: This code is distributed under the MIT license. Modified: 28 February 2012 Author: John Burkardt Parameters: Input, int M, the number of rows of the matrix. M must be positive. Input, int N, the number of columns of the matrix. N must be positive. Input, double A[M*N], the R8GE matrix. Input, char *TITLE, a title. */ { r8ge_print_some ( m, n, a, 1, 1, m, n, title ); return; } /******************************************************************************/ void r8ge_print_some ( int m, int n, double a[], int ilo, int jlo, int ihi, int jhi, char *title ) /******************************************************************************/ /* Purpose: R8GE_PRINT_SOME prints some of an R8GE matrix. Discussion: The R8GE storage format is used for a "general" M by N matrix. A physical storage space is made for each logical entry. The two dimensional logical array is mapped to a vector, in which storage is by columns. Licensing: This code is distributed under the MIT license. Modified: 28 February 2012 Author: John Burkardt Parameters: Input, int M, the number of rows of the matrix. M must be positive. Input, int N, the number of columns of the matrix. N must be positive. Input, double A[M*N], the R8GE matrix. Input, int ILO, JLO, IHI, JHI, designate the first row and column, and the last row and column to be printed. Input, char *TITLE, a title. */ { # define INCX 5 int i; int i2hi; int i2lo; int j; int j2hi; int j2lo; printf ( "\n" ); printf ( "%s\n", title ); /* Print the columns of the matrix, in strips of 5. */ for ( j2lo = jlo; j2lo <= jhi; j2lo = j2lo + INCX ) { j2hi = j2lo + INCX - 1; j2hi = i4_min ( j2hi, n ); j2hi = i4_min ( j2hi, jhi ); printf ( "\n" ); /* For each column J in the current range... Write the header. */ printf ( " Col: " ); for ( j = j2lo; j <= j2hi; j++ ) { printf ( "%7d ", j ); } printf ( "\n" ); printf ( " Row\n" ); printf ( " ---\n" ); /* Determine the range of the rows in this strip. */ i2lo = i4_max ( ilo, 1 ); i2hi = i4_min ( ihi, m ); for ( i = i2lo; i <= i2hi; i++ ) { /* Print out (up to) 5 entries in row I, that lie in the current strip. */ printf ( "%5d ", i ); for ( j = j2lo; j <= j2hi; j++ ) { printf ( "%12g ", a[i-1+(j-1)*m] ); } printf ( "\n" ); } } return; # undef INCX } /******************************************************************************/ double r8utt_det ( int n, double a[] ) /******************************************************************************/ /* Purpose: R8UTT_DET computes the determinant of a R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 15 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input, double A[N], the matrix. Output, double R8UTT_DET, the determinant of the matrix. */ { double det; det = pow ( a[0], n ); return det; } /******************************************************************************/ double *r8utt_indicator ( int n ) /******************************************************************************/ /* Purpose: R8UTT_INDICATOR sets up a R8UTT indicator matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Output, double A[N], the matrix. */ { double *a; int j; a = ( double * ) malloc ( n * sizeof ( double ) ); for ( j = 0; j < n; j++ ) { a[j] = ( double ) ( j + 1 ); } return a; } /******************************************************************************/ double *r8utt_inverse ( int n, double a[] ) /******************************************************************************/ /* Purpose: R8UTT_INVERSE computes the inverse of a R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input, double A[N], the matrix to be inverted. Output, double R8UTT_INVERSE[N], the inverse matrix. */ { double *b; double d; int i; int j; double *p; double *pn; double *pnn; /* Initialize B. */ d = 1.0 / a[0]; b = ( double * ) malloc ( n * sizeof ( double ) ); b[0] = d; for ( i = 1; i < n; i++ ) { b[i] = 0.0; } /* Set the strict upper triangle. */ p = ( double * ) malloc ( n * sizeof ( double ) ); p[0] = 0.0; for ( i = 1; i < n; i++ ) { p[i] = a[i]; } /* PN will hold powers of P. */ pn = ( double * ) malloc ( n * sizeof ( double ) ); pn[0] = 1.0; for ( i = 1; i < n; i++ ) { pn[i] = 0.0; } /* Add N-1 powers of strict upper triangle. */ for ( j = 1; j < n; j++ ) { d = - d / a[0]; pnn = r8utt_mm ( n, p, pn ); for ( i = 0; i < n; i++ ) { b[i] = b[i] + d * pnn[i]; pn[i] = pnn[i]; } free ( pnn ); } free ( p ); free ( pn ); return b; } /******************************************************************************/ double *r8utt_mm ( int n, double a[], double b[] ) /******************************************************************************/ /* Purpose: R8UTT_MM computes C = A * B, where A and B are R8UTT matrices. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrices. Input, double A[N], the first factor. Input, double B[N], the second factor. Output, double R8UTT_MM[N], the product. */ { double *c; double *d; double *e; int k; d = ( double * ) malloc ( n * sizeof ( double ) ); for ( k = 0; k < n; k++ ) { d[k] = b[n-1-k]; } e = r8utt_mv ( n, a, d ); c = ( double * ) malloc ( n * sizeof ( double ) ); for ( k = 0; k < n; k++ ) { c[k] = e[n-1-k]; } free ( d ); free ( e ); return c; } /******************************************************************************/ double *r8utt_mtm ( int n, double a[], double b[] ) /******************************************************************************/ /* Purpose: R8UTT_MTM computes C = A' * B, where A and B are R8UTT matrices. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Note that the result C is a dense matrix, of type R8GE. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrices. Input, double A[N], B[N], the factors. Output, double R8UTT_MTM[N*N], the product. */ { double *c; int i; int j; int k; c = ( double * ) malloc ( n * n * sizeof ( double ) ); for ( i = 0; i < n; i++ ) { for ( j = 0; j < n; j++ ) { c[i+j*n] = 0.0; for ( k = 0; k <= i4_min ( i, j ); k++ ) { c[i+j*n] = c[i+j*n] + a[i-k] * b[j-k]; } } } return c; } /******************************************************************************/ double *r8utt_mtv ( int n, double a[], double x[] ) /******************************************************************************/ /* Purpose: R8UTT_MTV computes b = A'*x, where A is an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input, double A[N], the matrix. Input, double X[N], the vector to be multiplied by A. Output, double R8UTT_MTV[N], the product A' * x. */ { double *b; int d; int i; int j; b = ( double * ) malloc ( n * sizeof ( double ) ); for ( j = 0; j < n; j++ ) { b[j] = 0.0; } for ( d = 0; d < n; d++ ) { for ( j = d; j < n; j++ ) { i = j - d; b[j] = b[j] + a[j-i] * x[i]; } } return b; } /******************************************************************************/ double *r8utt_mv ( int n, double a[], double x[] ) /******************************************************************************/ /* Purpose: R8UTT_MV computes b=A*x, where A is an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input, double A[N], the matrix. Input, double X[N], the vector to be multiplied by A. Output, double R8UTT_MV[N], the product A * x. */ { double *b; int d; int i; int j; b = ( double * ) malloc ( n * sizeof ( double ) ); for ( i = 0; i < n; i++ ) { b[i] = 0.0; } for ( d = 0; d < n; d++ ) { for ( j = d; j < n; j++ ) { i = j - d; b[i] = b[i] + a[j-i] * x[j]; } } return b; } /******************************************************************************/ void r8utt_print ( int n, double a[], char *title ) /******************************************************************************/ /* Purpose: R8UTT_PRINT prints an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 15 November 2015 Author: John Burkardt Parameters: Input, int N, the number of rows and columns of the matrix. Input, double A[N], the R8UTT matrix. Input, char *TITLE, a title. */ { r8utt_print_some ( n, a, 0, 0, n - 1, n - 1, title ); return; } /******************************************************************************/ void r8utt_print_some ( int n, double a[], int ilo, int jlo, int ihi, int jhi, char *title ) /******************************************************************************/ /* Purpose: R8UTT_PRINT_SOME prints some of an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 15 November 2015 Author: John Burkardt Parameters: Input, int N, the number of rows and columns of the matrix. Input, double A[N], the R8UT matrix. Input, int ILO, JLO, IHI, JHI, designate the first row and column, and the last row and column to be printed. 0 <= ILO <= IHI < M. 0 <= JLO <= JHI < N. Input, char *TITLE, a title. */ { # define INCX 5 int i; int i2hi; int i2lo; int j; int j2hi; int j2lo; printf ( "\n" ); printf ( "%s\n", title ); /* Print the columns of the matrix, in strips of 5. */ for ( j2lo = jlo; j2lo <= jhi; j2lo = j2lo + INCX ) { j2hi = j2lo + INCX - 1; j2hi = i4_min ( j2hi, n - 1 ); j2hi = i4_min ( j2hi, jhi ); printf ( "\n" ); printf ( " Col: " ); for ( j = j2lo; j <= j2hi; j++ ) { printf ( "%7d ", j ); } printf ( "\n" ); printf ( " Row\n" ); printf ( " ---\n" ); /* Determine the range of the rows in this strip. */ i2lo = i4_max ( ilo, 0 ); i2hi = i4_min ( ihi, n - 1 ); for ( i = i2lo; i <= i2hi; i++ ) { /* Print out (up to) 5 entries in row I, that lie in the current strip. */ printf ( "%4d ", i ); for ( j = j2lo; j <= j2hi; j++ ) { if ( j < i ) { printf ( " " ); } else { printf ( "%12g ", a[j-i] ); } } printf ( "\n" ); } } return; # undef INCX } /******************************************************************************/ double *r8utt_random ( int n, int *seed ) /******************************************************************************/ /* Purpose: R8UTT_RANDOM randomizes an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 15 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input/output, int *SEED, a seed for the random number generator. Output, double R8UTT_RANDOM[N], the R8UTT matrix. */ { double *a; a = r8vec_uniform_01_new ( n, seed ); return a; } /******************************************************************************/ double *r8utt_sl ( int n, double a[], double b[] ) /******************************************************************************/ /* Purpose: R8UTT_SL solves a linear system A*x=b with an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. No factorization of the upper triangular matrix is required. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input, double A[N], the R8UTT matrix. Input, double B[N], the right hand side. Output, double R8UTT_SL[N], the solution vector. */ { int i; int j; double *x; x = ( double * ) malloc ( n * sizeof ( double ) ); for ( j = 0; j < n; j++ ) { x[j] = b[j]; } for ( j = n - 1; 0 <= j; j-- ) { x[j] = x[j] / a[0]; for ( i = 0; i < j; i++ ) { x[i] = x[i] - a[j-i] * x[j]; } } return x; } /******************************************************************************/ double *r8utt_slt ( int n, double a[], double b[] ) /******************************************************************************/ /* Purpose: R8UTT_SLT solves a linear system A'*x=b with an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. No factorization of the upper triangular matrix is required. Licensing: This code is distributed under the MIT license. Modified: 16 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input, double A[N], the R8UTT matrix. Input, double B[N], the right hand side. Output, double R8UTT_SLT[N], the solution vector. */ { int i; int j; double *x; x = ( double * ) malloc ( n * sizeof ( double ) ); for ( j = 0; j < n; j++ ) { x[j] = b[j]; } for ( j = 0; j < n; j++ ) { x[j] = x[j] / a[0]; for ( i = j + 1; i < n; i++ ) { x[i] = x[i] - x[j] * a[i-j]; } } return x; } /******************************************************************************/ double *r8utt_to_r8ge ( int n, double a_utt[] ) /******************************************************************************/ /* Purpose: R8UTT_TO_R8GE copies an R8UTT matrix to an R8GE matrix. Discussion: The R8GE storage format is used for a general M by N matrix. A storage space is made for each entry. The two dimensional logical array can be thought of as a vector of M*N entries, starting with the M entries in the column 1, then the M entries in column 2 and so on. Considered as a vector, the entry A(I,J) is then stored in vector location I+(J-1)*M. The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 14 November 2015 Author: John Burkardt Parameters: Input, int N, the order of the matrix. Input, double A_UTT[N], the R8UTT matrix. Output, double R8UTT_TO_R8GE[N*N], the R8GE matrix. */ { double *a_ge; int d; int i; int j; a_ge = ( double * ) malloc ( n * n * sizeof ( double ) ); for ( j = 0; j < n; j++ ) { for ( i = 0; i < n; i++ ) { a_ge[i+j*n] = 0.0; } } for ( d = 0; d < n; d++ ) { for ( j = d; j < n; j++ ) { i = j - d; a_ge[i+j*n] = a_utt[j-i]; } } return a_ge; } /******************************************************************************/ double *r8utt_zeros ( int n ) /******************************************************************************/ /* Purpose: R8UTT_ZEROS zeros an R8UTT matrix. Discussion: The R8UTT storage format is used for an N by N upper triangular Toeplitz matrix. Licensing: This code is distributed under the MIT license. Modified: 15 November 2015 Author: John Burkardt Parameters: Input, int N, the number of rows and columns of the matrix. Output, double R8UTT_ZEROS[M*N], the R8UTT matrix. */ { double *a; int i; a = ( double * ) malloc ( n * sizeof ( double ) ); for ( i = 0; i < n; i++ ) { a[i] = 0.0; } return a; } /******************************************************************************/ double *r8vec_indicator1_new ( int n ) /******************************************************************************/ /* Purpose: R8VEC_INDICATOR1_NEW sets an R8VEC to the indicator1 vector {1,2,3...}. Licensing: This code is distributed under the MIT license. Modified: 26 August 2008 Author: John Burkardt Parameters: Input, int N, the number of elements of A. Output, double R8VEC_INDICATOR1_NEW[N], the array. */ { double *a; int i; a = ( double * ) malloc ( n * sizeof ( double ) ); for ( i = 0; i <= n-1; i++ ) { a[i] = ( double ) ( i + 1 ); } return a; } /******************************************************************************/ void r8vec_print ( int n, double a[], char *title ) /******************************************************************************/ /* Purpose: R8VEC_PRINT prints an R8VEC. Discussion: An R8VEC is a vector of R8's. Licensing: This code is distributed under the MIT license. Modified: 08 April 2009 Author: John Burkardt Parameters: Input, int N, the number of components of the vector. Input, double A[N], the vector to be printed. Input, char *TITLE, a title. */ { int i; printf ( "\n" ); printf ( "%s\n", title ); printf ( "\n" ); for ( i = 0; i < n; i++ ) { printf ( " %8d %14f\n", i, a[i] ); } return; } /******************************************************************************/ double *r8vec_uniform_01_new ( int n, int *seed ) /******************************************************************************/ /* Purpose: R8VEC_UNIFORM_01_NEW returns a unit pseudorandom R8VEC. Discussion: This routine implements the recursion seed = 16807 * seed mod ( 2^31 - 1 ) unif = seed / ( 2^31 - 1 ) The integer arithmetic never requires more than 32 bits, including a sign bit. Licensing: This code is distributed under the MIT license. Modified: 19 August 2004 Author: John Burkardt Reference: Paul Bratley, Bennett Fox, Linus Schrage, A Guide to Simulation, Second Edition, Springer, 1987, ISBN: 0387964673, LC: QA76.9.C65.B73. Bennett Fox, Algorithm 647: Implementation and Relative Efficiency of Quasirandom Sequence Generators, ACM Transactions on Mathematical Software, Volume 12, Number 4, December 1986, pages 362-376. Pierre L'Ecuyer, Random Number Generation, in Handbook of Simulation, edited by Jerry Banks, Wiley, 1998, ISBN: 0471134031, LC: T57.62.H37. Peter Lewis, Allen Goodman, James Miller, A Pseudo-Random Number Generator for the System/360, IBM Systems Journal, Volume 8, Number 2, 1969, pages 136-143. Parameters: Input, int N, the number of entries in the vector. Input/output, int *SEED, a seed for the random number generator. Output, double R8VEC_UNIFORM_01_NEW[N], the vector of pseudorandom values. */ { int i; const int i4_huge = 2147483647; int k; double *r; if ( *seed == 0 ) { fprintf ( stderr, "\n" ); fprintf ( stderr, "R8VEC_UNIFORM_01_NEW - Fatal error!\n" ); fprintf ( stderr, " Input value of SEED = 0.\n" ); exit ( 1 ); } r = ( double * ) malloc ( n * sizeof ( double ) ); for ( i = 0; i < n; i++ ) { k = *seed / 127773; *seed = 16807 * ( *seed - k * 127773 ) - k * 2836; if ( *seed < 0 ) { *seed = *seed + i4_huge; } r[i] = ( double ) ( *seed ) * 4.656612875E-10; } return r; }