This commit is contained in:
Daniel Knüttel 2018-11-11 18:49:43 +01:00
commit 49d42cdd68
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// Daniel Knüttel Aufgabe2
/*
* Copyright(c) 2018 Daniel Knüttel
*/
/* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Dieses Programm ist Freie Software: Sie können es unter den Bedingungen
* der GNU General Public License, wie von der Free Software Foundation,
* Version 3 der Lizenz oder (nach Ihrer Wahl) jeder neueren
* veröffentlichten Version, weiterverbreiten und/oder modifizieren.
*
* Dieses Programm wird in der Hoffnung, dass es nützlich sein wird, aber
* OHNE JEDE GEWÄHRLEISTUNG, bereitgestellt; sogar ohne die implizite
* Gewährleistung der MARKTFÄHIGKEIT oder EIGNUNG FÜR EINEN BESTIMMTEN ZWECK.
* Siehe die GNU General Public License für weitere Details.
*
* Sie sollten eine Kopie der GNU General Public License zusammen mit diesem
* Programm erhalten haben. Wenn nicht, siehe <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
/*
* \brief Computes the householder partition of A.
* Stores the generating vectors of Q in the memory passed as A,
* the diagonal elements in alpha and the rest of R in the memory
* passed as A.
*
* \param A Matrix to partition. After the partition this memory contains Q and R.
* \param alpha Will be filled with diagonal elements of R.
* \param n Length of A[i].
* \param m Length of A.
* \return Status.
* */
int householder(double ** A, double * alpha, int n, int m);
/*
* \brief Computes the solution of and n times n system using a QR partition.
* Overwrites b.
*
* \param A Matrix that has been modified by the function householder.
* \param alpha Diagonal elements of R, produced by the function householder.
* \param n Length of A and A[i].
* \param b Vector b for Ax=b. Will be overwritten with elements of x.
* \return Status.
* */
int solve_QR(double ** A, double * alpha, int n, double * b);
/*
* \brief Computes Q^Tb and stores the result in b.
*
* \param A Matrix that has been modified by the function householder.
* \param alpha Diagonal elements of R, produced by the function householder.
* \param n Length of A and A[i].
* \param b Vector b for Ax=b. Will be overwritten with elements of the result.
*
* \return Status.
* */
int qtb(double ** A, double * alpha, int n, double * b);
/*
*
* \brief Uses backwards substitution to solve R = Q^Tb.
*
* \param A Matrix that has been modified by the function householder.
* \param alpha Diagonal elements of R, produced by the function householder.
* \param n Length of A and A[i].
* \param b Vector b for Ax=b. Will be overwritten with elements of the result.
*
* \return Status.
*
* */
int rw_subs(double ** A, double * alpha, int n, double * b);
/*
* \brief Print the matrix in a nicely formatted way to stream.
*
* \param stream The output stream.
* \param matrix The matrix to print.
* \param n Length of matrix[i].
* \param m Length of matrix.
*
* */
int fprintm(FILE * stream, double ** matrix, int n, int m);
/*
* \brief Print the vector in a nicely formatted way to stream.
*
* \param stream The output stream.
* \param vector The vector to print.
* \param n Length of vector.
*
* */
int fprintv(FILE * stream, double * vector, int n);
#define printm(matrix, n, m) fprintm(stdout, matrix, n, m)
#define printv(vector, n) fprintv(stdout, vector, n)
int main(void)
{
int status = 0;
return status;
}
int householder(double ** A, double * alpha, int n, int m)
{
int i, j;
for(i = 0; i < n; i++)
{
// Bring this column in triangular shape.
}
}

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import copy
import pprint
import numpy
def gaussian_with_pivot(A, b, round = lambda x: x):
A = numpy.array(A, dtype = numpy.float64)
b = numpy.array(b, dtype = numpy.float64)
L = numpy.identity(len(A), dtype = numpy.float64)
s = numpy.zeros(len(A), dtype = numpy.float64)
for k in range(len(A)):
max_a = numpy.absolute(A[k:,k]).argmax()
A[[k, k + max_a]] = A[[k + max_a, k]]
b[[k, k + max_a]] = b[[k + max_a, k]]
s[k] = k + max_a
for i in range(k + 1, len(A)):
L[i][k] = round(A[i][k]/A[k][k])
b[i] = round(b[i] - round(L[i][k] * b[k]))
for j in range(k + 1, len(A)):
A[i][j] = round(A[i][j] - round(L[i][k] * A[k][j]))
A[i][k] = 0
return A, b, L, s
def gaussian_no_pivot(A, b, round = lambda x: x):
A = numpy.array(A, dtype = numpy.float64)
b = numpy.array(b, dtype = numpy.float64)
L = numpy.identity(len(A), dtype = numpy.float64)
for k in range(len(A)):
for i in range(k + 1, len(A)):
L[i][k] = round(A[i][k]/A[k][k])
b[i] = round(b[i] - round(L[i][k] * b[k]))
for j in range(k + 1, len(A)):
A[i][j] = round(A[i][j] - round(L[i][k] * A[k][j]))
A[i][k] = 0
return A, b, L
if( __name__ == "__main__"):
# For Exercise 1
A = [[10, 1, 0], [15, 2, 1], [5, 0, 1]]
b = [12, 18, 4]
pprint.pprint(gaussian_with_pivot(A, b))
# For Exercise 2
A = [[7, 1, 1]
, [10, 1, 1]
, [1000, 0, 1]]
b = [10, 13, 1001]
pprint.pprint(A)
def round4(x):
return float("%.4g" % x)
pprint.pprint(gaussian_with_pivot(A, b, round4))
pprint.pprint(gaussian_no_pivot(A, b, round4))
A = numpy.zeros((10, 10))
for i in range(10):
if(i - 1 > 0):
A[i][i - 1] = -1
A[i][i] = 2
if(i + 1 < 10):
A[i][i + 1] = -1
pprint.pprint(gaussian_no_pivot(A, numpy.ones(10)))