calculus.edp

FreeFem++可以生成高质量的有限元网格。可以用于流体力学

real  x=3.14,y;
int  i,j;
complex c;
cout << " x = " << x << "\n";

x = 1;y=2;
x=y;

i=0;j=1;

cout << 1 + 3 << " " <<  1/3 << "\n";
cout << 10 ^10   << "\n";
cout << 10 ^-10   << "\n";
cout << -10^-2+5   << "== 4.99 \n";
cout << 10^-2+5    << "==  5.01 \n";
cout << "------------------ complex ---- \n" ;
cout << 10-10i   << " \n";
int prec=cout.precision(12);
cout.scientific << " scientific : \n"; 
cout << " -1^(1/3) = " << (-1+0i)^(1./3.)   << " (precision=12)\n";
cout.precision(prec);
cout.fixed;
cout.showpos << " fixed and showpos :\n";
cout << " -1^(1/3) = " << (-1+0i)^(1./3.)   << " (precision="<<prec << ")\n";
cout.noshowpos << "noshowpos\n"; 
cout << " 8^(1/3)= " << (8)^(1./3.)   << " \n";
cout << " sqrt(-1) = " << sqrt(-1+0i) << " \n";
complex a=10+1i;
cout.default << "default \n";
cout << a << endl;
cout << " real(a) = " <<real(a) << " conj(a)" << conj(a) 
     << " arg(a) = " << arg(a) << endl;

cout << " ++i =" <<  ++i ;
cout <<  " i=" << i << "\n";
cout << " i++ = "<< i++ << "\n";
cout << " i   = " << i << "\n";
// ----  string concatenation ----------
 string str,str1;
 str="abc+";
 str1="+abcddddd+";
 str=str + str1;
 str = str + 2 ;
 cout << "str=  " << str << "== abc++abcddddd+2;\n";
 
 { real x=0;
 for (int i=0;i<10;i++)
   x += i*i;
 cout << " x= " << x << endl;
 // example of if arithmetic expression 
 real a =  x == 0 ? x : -1;
 real b =  x != 0 ? x : -1;
 cout << " a = " << a << " b = " << b << endl; 
 }