Интеграл с параметром для процедуры

restart
Digits:= 5;
x1:=1;
x2:= 1;
x3:= 1;
 
b := proc (x1, x2, x3, x4)
b := x2*x1+x3+x4/7 
end proc; 
b(x1, x2, x3, x4)
 
evalf(Int(6+b(x1, x2, x3, x4)-14*b(x1, x2, x3, x4), x4 = 0 .. 2)) assuming b(x1, x2, x3, x4) < 2;

> for x4 from 0 to 2 do
> A:=evalf(b(x1,x2,x3,x4)):
> if A<2 then 
> # [считаем то, что нужно считать при A<2] 
> end if;
> end do;

restart
Digits:= 5;
x1:=1;
x2:= 1;
x3:= 1;
 
b := proc (x1, x2, x3, x4)
b := x2*x1+x3+x4/2 
end proc; 
b(x1, x2, x3, x4)
 
for x4 from 0 to 2 do 
A := evalf(b(x1, x2, x3, x4)); 
if A <= 2.5 then 
S := evalf(Int(6+A-14*A, x4 = 0 .. 2));
end if;
end do; 
value(Iy);

> restart: Digits:= 5: x1:=1: x2:= 1: x3:= 1:
> b := proc (a1, a2, a3, a4)
local b;
b := a2*a1+a3+a4/2; 
end proc:
> S:=0:
for Z from 0 to 2 do
if b(x1, x2, x3, Z)<=2.5 then
S := S + (Int(6+b(x1, x2, x3, x4)-14*b(x1, x2, x3, x4), x4 = 0 .. 2)):
end if:
end do;
> print("Summa = ",evalf(S)); 
 
                         "Summa = ", -106.00

plot3d(evalf(S), x1 = -2 ..2, x2 = -2 .. 2);

restart; 
Digits := 5; 
x1; 
x2; 
x3 := 1;
 
b := proc (a1, a2, a3, a4) 
local b; 
b := a2*a1+a3+(1/2)*a4 
end proc;
 
S := 0; for Z from 0 to 2 do 
if b(x1, x2, x3, Z)<=2.5 then
S := S + (Int(6+b(x1, x2, x3, x4)-14*b(x1, x2, x3, x4), x4 = 0 .. 2)):
end if 
end do;
 
print("Summa = ", evalf(S));
                    
plot3d(evalf(S), x1 = -0.06 ..0.06, x2 = -0.06 .. 0.06);

plot3d(evalf(S), x1 = -1 ..1, x2 = -1 .. 1);