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Sample code from Math.h++

This page provides three brief samples of code, for linear algebra, subscripting, and signal processing. From here, you can also access:

The technical description of Math.h++
A description of the classes available in Math.h++
Comments from users of Math.h++

Linear Algebra

Read in a matrix, compute the LU factorization, and use the decomposition to solve for multiple right hand sides.

DoubleGenMat A;
cin>> A;			//read in the matrix A
DoubleGenFact LU(A);		//compute LU decomposition
if (!LU.good ( ) )  		//check that LU is OK
    cerr  << "Problem constructing LU.  Perhaps A is singular"  <<  endl;   else 
DoubleVec b;
while ( cin>> b ) 		//read in right hand sides
DoubleVec x = solve (LU, b);
cout << x >> endl;		//print solution

Subscripting

Example 1

Set up block matrix
1  1  1  2  2  2
1  1  1  2  2  2
1  1  1  2  2  2
3  3  3  4  4  4
3  3  3  4  4  4
3  3  3  4  4  4
DoubleGenMat A(6, 6);
RWSlice I(0,3);	//slice starts at 0, length 3
RWToEnd J(3);	//index from 3 to the end
A (I, I) = 1;
A (I, J) = 2;
A (J, I) = 3;
A (J, J) = 4;

Example 2

View planes of data in a 3-D array: (note no data copying is done)

DoubleArray A(10, 10, 10);
DoubleGenMat xyplane = A(5, RWAll, RWAll);
DoubleGenMat xzplane = A(RWAll, 5, RWAll);
DoubleGenMat yzplane = A(RWAll, RWAll, 5);

Signal Processing

Compute FFT of a vector. Work arrays and vector size are computed in the FFT server.

DComplexVec a;				//construct a vector
cin >> A;				//read it in
DComplexFFTServer s;			//construct a server
DComplexVec transform = s.fourier (a);	//compute transform
cout << transform;			//print it out