#include <math.h>
#include <stdio.h>
double const pi = 3.1415926535897932385;
static double pyr(double x, double t){
  if(t<0) return pyr(x, -t);
  if(x<0) return pyr(-x, t);
  if(t>pi) return -pyr(x, t-pi);
  if(x>pi) return -pyr(x-pi, t);
  if(x>pi/2) return -pyr(pi-x, t);
  if(t>pi/2) return -pyr(x, pi-t);
  if(x<t) return pyr(t, x);
  return 1.-2.*x/pi;}
static double fs(double x, double t, int n){
  double s = 0;
  while (n--) if(n&1) s += cos(n*x)*cos(n*t)/(n*n);
  return 8./(pi*pi)*s;}
static void rp(double x, double t){
  printf("%11.6f %11.6f %16.11f %16.11f\n", x, t, pyr(x,t), fs(x,t,10000));}
int main(){
  rp(0,0); rp(pi/2,0); rp(pi/2-.0001, 0); rp(1,0); rp(.1, .2);
  rp(.1,.3); rp(2, pi/2); rp(.2, 1.45); rp(2, 1.7);
  rp(-1,4); rp(-3,-5);
  rp(pi-2, 7-2*pi); rp(2, 7-2*pi); rp(2,7); rp(2.,-7);
  return 0;}

/*
   0.000000    0.000000    1.00000000000    0.99995947153
   1.570796    0.000000    0.00000000000    0.00000000000
   1.570696    0.000000    0.00006366198    0.00006365857
   1.000000    0.000000    0.36338022763    0.36338022616
   0.100000    0.200000    0.87267604553    0.87267606380
   0.100000    0.300000    0.80901406829    0.80901407422
   2.000000    1.570796   -0.00000000000   -0.00000000000
   0.200000    1.450000    0.07690133007    0.07690133160
   2.000000    1.700000    0.08225361302    0.08225361833
  -1.000000    4.000000   -0.36338022763   -0.36338023706
  -3.000000   -5.000000   -0.18309886184   -0.18309885929
   1.141593    0.716815    0.27323954474    0.27323954429
   2.000000    0.716815   -0.27323954474   -0.27323954429
   2.000000    7.000000   -0.27323954474   -0.27323954429
   2.000000   -7.000000   -0.27323954474   -0.27323954429
*/