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vecmat3 added explicit linear solver

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This commit is contained in:
Jiri Pittner 2023-12-20 18:00:15 +01:00
parent 731b2a128d
commit eafcfbdd00
3 changed files with 43 additions and 3 deletions
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19
t.cc
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@ -2792,6 +2792,25 @@ if(sizeof(int)!=read(f,&seed,sizeof(int))) laerror("cannot read /dev/random");
close(f);
srand(seed);
Mat3<double> a;
a.randomize(10.);
cout<<a<<endl;
Vec3<double> b;
b.randomize(10.);
cout <<b<<endl;
Vec3<double> x = a.linear_solve(b);
cout <<x<<endl;
cout <<"linear solve error = "<<(b-a*x).norm()<<endl;
}
if(0)
{
int seed;
int f=open("/dev/random",O_RDONLY);
if(sizeof(int)!=read(f,&seed,sizeof(int))) laerror("cannot read /dev/random");
close(f);
srand(seed);
Mat3<double> a;
a.randomize(10.);
cout<<a<<endl;

24
vecmat3.cc
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@ -207,7 +207,7 @@ void Mat3<T>::transposeme()
{T t; t=q[0][1]; q[0][1]=q[1][0]; q[1][0]=t; t=q[0][2]; q[0][2]=q[2][0]; q[2][0]=t; t=q[1][2]; q[1][2]=q[2][1]; q[2][1]=t;};
template<typename T>
const Mat3<T> Mat3<T>::inverse() const
const Mat3<T> Mat3<T>::inverse(T *det) const
{
Mat3<T> r;
r[0][0]= q[2][2]*q[1][1]-q[2][1]*q[1][2];
@ -219,7 +219,27 @@ const Mat3<T> Mat3<T>::inverse() const
r[2][0]= q[2][1]*q[1][0]-q[2][0]*q[1][1];
r[2][1]= -q[2][1]*q[0][0]+q[2][0]*q[0][1];
r[2][2]= q[1][1]*q[0][0]-q[1][0]*q[0][1];
return r/determinant();
T d=determinant();
if(det) *det=d;
return r/d;
}
template<typename T>
const Vec3<T> Mat3<T>::linear_solve(const Vec3<T> &rhs, T *det) const
{
Vec3<T> r;
r[0]= ( q[2][2]*q[1][1]-q[2][1]*q[1][2]) * rhs[0]
+( -q[2][2]*q[0][1]+q[2][1]*q[0][2]) * rhs[1]
+( +q[1][2]*q[0][1]-q[1][1]*q[0][2]) * rhs[2];
r[1]= (-q[2][2]*q[1][0]+q[2][0]*q[1][2]) * rhs[0]
+( +q[2][2]*q[0][0]-q[2][0]*q[0][2]) * rhs[1]
+( -q[1][2]*q[0][0]+q[1][0]*q[0][2]) * rhs[2];
r[2]= ( q[2][1]*q[1][0]-q[2][0]*q[1][1]) * rhs[0]
+( -q[2][1]*q[0][0]+q[2][0]*q[0][1]) *rhs[1]
+( q[1][1]*q[0][0]-q[1][0]*q[0][1]) * rhs[2];
T d=determinant();
if(det) *det=d;
return r/d;
}
template<typename T>

3
vecmat3.h
View File

@ -172,7 +172,8 @@ public:
T determinant() const;
void transposeme();
const Mat3 transpose() const {Mat3 r(*this); r.transposeme(); return r;};
const Mat3 inverse() const;
const Mat3 inverse(T *det = NULL) const;
const Vec3<T> linear_solve(const Vec3<T> &rhs, T *det = NULL) const;
//C-style IO
int fprintf(FILE *f, const char *format) const {int n= ::fprintf(f,format,q[0][0],q[0][1],q[0][2]); n+=::fprintf(f,format,q[1][0],q[1][1],q[1][2]); n+=::fprintf(f,format,q[2][0],q[2][1],q[2][2]); return n;};
int fscanf(FILE *f, const char *format) const {return ::fscanf(f,format,q[0][0],q[0][1],q[0][2]) + ::fscanf(f,format,q[1][0],q[1][1],q[1][2]) + ::fscanf(f,format,q[2][0],q[2][1],q[2][2]);};