/****************
  example1.c by Michael J. Scott April 15, 1997   for ME171
  demonstrates use of matrix.h and matrix.c
  (get from http://www.design.caltech.edu/Courses/ME171/)
  compile command is: gcc -g -Wall -o example1 matrix.c example1.c 
***********/

#include <stdio.h>
#include <stdlib.h>
#include "matrix.h"
#define VECTORS 8

void main(){

  FILE *fpin,*fpout;
  int i,j;
  double t1[N][N]={{1,0,0,0},{0,1,0,0},{0,0,1,0},{-6,-8,-7.5,1}};
  double t2[N][N]={{1,0,0,0},{0,0,-1,0},{0,1,0,0},{0,0,0,1}};
  double t[N][N];
  double vec[VECTORS][N],tempvec[N];

  /******* read in the data file ********/
  fpin = fopen("in.dat","r");
  for(i=0;i<VECTORS;i++){
    for(j=0;j<3;j++){
      if(fscanf(fpin,"%lf",&vec[i][j])==0){
	printf("Trouble reading data. Exiting.\n");
	exit(1);
      }
    }
    vec[i][3]=1.;
  }
  fclose(fpin);

  /******** perform calculations *******/
  sq_mat_by_mat(t1,t2,t);  
  for(i=0;i<VECTORS;i++){
    row_by_mat(vec[i],t,tempvec);  /* can't use vec[i] as output! */
    for(j=0;j<N;j++) vec[i][j]=tempvec[j];
  }

  /******* write the output file *******/
  fpout = fopen("out.dat","w");
  for(i=0;i<VECTORS;i++){
    for(j=0;j<2;j++){
      fprintf(fpout,"%.2f ",vec[i][j]);
    }
    fprintf(fpout,"\n");
  }
  fclose(fpout);
}