function foo(xTab, yTab) {
sum = 0.0;
for (i = 1; i < xTab.length; ++i) {
sum += (xTab[i-1] - xTab[i]) * (yTab[i-1] - yTab[i]);
}
return sum / 2.0;
}
xTab = [1,2,3,4,5];
yTab = [2,4,6,8,10];
print(foo(xTab, yTab));
ZnVuY3Rpb24gZm9vKHhUYWIsIHlUYWIpIHsKICAgIHN1bSA9IDAuMDsKCWZvciAoaSA9IDE7IGkgPCB4VGFiLmxlbmd0aDsgKytpKSB7CgkJc3VtICs9ICh4VGFiW2ktMV0gLSB4VGFiW2ldKSAqICh5VGFiW2ktMV0gLSB5VGFiW2ldKTsKCX0KCXJldHVybiBzdW0gLyAyLjA7Cn0KCnhUYWIgPSBbMSwyLDMsNCw1XTsKeVRhYiA9IFsyLDQsNiw4LDEwXTsKCnByaW50KGZvbyh4VGFiLCB5VGFiKSk7