Советы по Delphi

Вычислитель математических формул


Вот что я обнаружил несколько дней назад при просмотре зарубежных источников:

FORMULA должна быть стокой, содержащей формулу. Допускаются переменные x, y и z, а также операторы, перечисленные ниже. Пример:

    sin(x)*cos(x^y)+exp(cos(x))

Использование:



    uses EVALCOMP;

var calc:    EVALVEC ; (evalvec - указатель на объект, определяемый evalcomp)
FORMULA: string;
begin

FORMULA:='x+y+z';

new (calc,init(FORMULA)); (Построение дерева оценки)

writeln ( calc^.eval1d(7) )     ; (x=7 y=0 z=0; result:  7)
writeln ( calc^.eval2d(7,8) )   ; (x=7 y=8 z=0; result: 15)
writeln ( calc^.eval3d(7,8,9) ) ; (x=7 y=8 z=9; result: 24)

dispose(calc,done); (разрушение дерева оценки)

end.

Допустимые операторы:

    x <l;> y ; Логические операторы возвращают 1 в случае истины и 0 если ложь.
x <l;= y
x >= y
x > y
x <l; y
x = y
x + y
x - y
x eor y ( исключающее или )
x or y
x * y
x / y
x and y
x mod y
x div y
x ^ y ( степень )
x shl y
x shr y
not (x)
sinc (x)
sinh (x)
cosh (x)
tanh (x)
coth (x)
sin (x)
cos (x)
tan (x)
cot (x)
sqrt (x)
sqr (x)
arcsinh (x)
arccosh (x)
arctanh (x)
arccoth (x)
arcsin (x)
arccos (x)
arctan (x)
arccot (x)
heavy (x) ; 1 для положительных чисел, 0 для остальных
sgn (x) ; 1 для положительных чисел, -1 для отрицательных и 0 для нуля
frac (x)
exp (x)
abs (x)
trunc (x)
ln (x)
odd (x)
pred (x)
succ (x)
round (x)
int (x)
fac (x) ; x*(x-1)*(x-2)*...*3*2*1
rnd ; Случайное число в диапазоне [0,1]
rnd (x) ; Случайное число в диапазоне [0,x]
pi
e

    unit evalcomp;

interface

type fun= function(x,y:real):real;
evalvec= ^evalobj; evalobj= object f1,f2:evalvec; f1x,f2y:real; f3:fun; function eval:real; function eval1d(x:real):real; function eval2d(x,y:real):real; function eval3d(x,y,z:real):real; constructor init(st:string); destructor done; end; var  evalx,evaly,evalz:real;

implementation

var analysetmp:fun;

function search (text,code:string; var pos:integer):boolean;
var i,count:integer;
flag:boolean; newtext:string; begin
if length(text)<l;length(code) then begin search:=false; exit; end; flag:=false; pos:=length(text)-length(code)+1; repeat if code=copy(text,pos,length(code)) then flag:=true else dec(pos); if flag then begin count:=0; for i:= pos+1 to length(text) do begin if copy(text,i,1) = '(' then inc(count); if copy(text,i,1) = ')' then dec(count); end; if count<l;>0 then begin dec(pos); flag:=false; end; end; until (flag=true) or (pos=0); search:=flag; end;

function myid(x,y:real):real;
begin
myid:=x; end;

function myunequal(x,y:real):real;
begin
if x<>y then myunequal:=1 else myunequal:=0; end;

function mylessequal(x,y:real):real;
begin
if x<=y then mylessequal:=1 else mylessequal:=0; end;

function mygreaterequal(x,y:real):real;
begin
if x>=y then mygreaterequal:=1 else mygreaterequal:=0; end;

function mygreater(x,y:real):real;
begin
if x>y then mygreater:=1 else mygreater:=0; end;

function myless(x,y:real):real;
begin
if x<y then myless:=1 else myless:=0; end;

function myequal(x,y:real):real;
begin
if x=y then myequal:=1 else myequal:=0; end;

function myadd(x,y:real):real;
begin
myadd:=x+y; end;

function mysub(x,y:real):real;
begin
mysub:=x-y; end;

function myeor(x,y:real):real;
begin
myeor:=trunc(x) xor trunc(y); end;

function myor(x,y:real):real;
begin
myor:=trunc(x) or trunc(y); end;

function mymult(x,y:real):real;
begin
mymult:=x*y; end;

function mydivid(x,y:real):real;
begin
mydivid:=x/y; end;

function myand(x,y:real):real;
begin
myand:=trunc(x) and trunc(y); end;

function mymod(x,y:real):real;
begin
mymod:=trunc(x) mod trunc(y); end;

function mydiv(x,y:real):real;
begin
mydiv:=trunc(x) div trunc(y); end;

function mypower(x,y:real):real;
begin
if x=0 then mypower:=0 else if x>0 then mypower:=exp(y*ln(x)) else if trunc(y)<>y  then begin writeln (' Немогу вычислить x^y '); halt; end else if odd(trunc(y))=true then mypower:=-exp(y*ln(-x)) else mypower:=exp(y*ln(-x)) end;

function myshl(x,y:real):real;
begin
myshl:=trunc(x) shl trunc(y); end;

function myshr(x,y:real):real;
begin
myshr:=trunc(x) shr trunc(y); end;

function mynot(x,y:real):real;
begin
mynot:=not trunc(x); end;

function mysinc(x,y:real):real;
begin
if x=0 then
mysinc:=1 else
mysinc:=sin(x)/x end;

function mysinh(x,y:real):real;
begin
mysinh:=0.5*(exp(x)-exp(-x))
end;

function mycosh(x,y:real):real;
begin
mycosh:=0.5*(exp(x)+exp(-x))
end;

function mytanh(x,y:real):real;
begin
mytanh:=mysinh(x,0)/mycosh(x,0)
end;

function mycoth(x,y:real):real;
begin
mycoth:=mycosh(x,0)/mysinh(x,0)
end;

function mysin(x,y:real):real;
begin
mysin:=sin(x)
end;

function mycos(x,y:real):real;
begin
mycos:=cos(x)
end;

function mytan(x,y:real):real;
begin
mytan:=sin(x)/cos(x)
end;

function mycot(x,y:real):real;
begin
mycot:=cos(x)/sin(x)
end;

function mysqrt(x,y:real):real;
begin
mysqrt:=sqrt(x)
end;

function mysqr(x,y:real):real;
begin
mysqr:=sqr(x)
end;

function myarcsinh(x,y:real):real;
begin
myarcsinh:=ln(x+sqrt(sqr(x)+1))
end;

function mysgn(x,y:real):real;
begin
if x=0 then
mysgn:=0 else
mysgn:=x/abs(x) end;

function myarccosh(x,y:real):real;
begin
myarccosh:=ln(x+mysgn(x,0)*sqrt(sqr(x)-1))
end;

function myarctanh(x,y:real):real;
begin
myarctanh:=ln((1+x)/(1-x))/2
end;

function myarccoth(x,y:real):real;
begin
myarccoth:=ln((1-x)/(1+x))/2
end;

function myarcsin(x,y:real):real;
begin
if x=1 then
myarcsin:=pi/2 else
myarcsin:=arctan(x/sqrt(1-sqr(x))) end;

function myarccos(x,y:real):real;
begin
myarccos:=pi/2-myarcsin(x,0)
end;

function myarctan(x,y:real):real;
begin
myarctan:=arctan(x);
end;

function myarccot(x,y:real):real;
begin
myarccot:=pi/2-arctan(x)
end;

function myheavy(x,y:real):real;
begin
myheavy:=mygreater(x,0)
end;

function myfrac(x,y:real):real;
begin
myfrac:=frac(x)
end;

function myexp(x,y:real):real;
begin
myexp:=exp(x)
end;

function myabs(x,y:real):real;
begin
myabs:=abs(x)
end;

function mytrunc(x,y:real):real;
begin
mytrunc:=trunc(x)
end;

function myln(x,y:real):real;
begin
myln:=ln(x)
end;

function myodd(x,y:real):real;
begin
if odd(trunc(x)) then
myodd:=1 else
myodd:=0; end;

function mypred(x,y:real):real;
begin
mypred:=pred(trunc(x));
end;

function mysucc(x,y:real):real;
begin
mysucc:=succ(trunc(x));
end;

function myround(x,y:real):real;
begin
myround:=round(x);
end;

function myint(x,y:real):real;
begin
myint:=int(x);
end;

function myfac(x,y:real):real;
var n : integer;
r : real; begin
if x<0 then begin writeln(' Немогу вычислить факториал '); halt; end;
if x = 0 then myfac := 1
else
begin r := 1; for n := 1 to trunc ( x ) do r := r * n; myfac:= r; end; end;

function myrnd(x,y:real):real;
begin
myrnd:=random;
end;

function myrandom(x,y:real):real;
begin
myrandom:=random(trunc(x));
end;

function myevalx(x,y:real):real;
begin
myevalx:=evalx;
end;

function myevaly(x,y:real):real;
begin
myevaly:=evaly;
end;

function myevalz(x,y:real):real;
begin
myevalz:=evalz;
end;

procedure analyse (st:string; var st2,st3:string);
label start;
var pos:integer; value:real; newterm,term:string; begin
term:=st;
start:
if term='' then begin analysetmp:=myid; st2:='0'; st3:=''; exit; end; newterm:=''; for pos:= 1 to length(term) do if copy(term,pos,1)<>' ' then newterm:=newterm+copy(term,pos,1); term:=newterm; if term='' then begin analysetmp:=myid; st2:='0'; st3:=''; exit; end; val(term,value,pos); if pos=0 then begin analysetmp:=myid; st2:=term; st3:=''; exit; end; if search(term,'<>',pos) then begin analysetmp:=myunequal; st2:=copy(term,1,pos-1); st3:=copy(term,pos+2,length(term)-pos-1); exit; end; if search(term,'<=',pos) then begin analysetmp:=mylessequal; st2:=copy(term,1,pos-1); st3:=copy(term,pos+2,length(term)-pos-1); exit; end; if search(term,'>=',pos) then begin analysetmp:=mygreaterequal; st2:=copy(term,1,pos-1); st3:=copy(term,pos+2,length(term)-pos-1); exit; end; if search(term,'>',pos) then begin analysetmp:=mygreater; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'<',pos) then begin analysetmp:=myless; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'=',pos) then begin analysetmp:=myequal; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'+',pos) then begin analysetmp:=myadd; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'-',pos) then begin analysetmp:=mysub; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'eor',pos) then begin analysetmp:=myeor; st2:=copy(term,1,pos-1); st3:=copy(term,pos+3,length(term)-pos-2); exit; end; if search(term,'or',pos) then begin analysetmp:=myor; st2:=copy(term,1,pos-1); st3:=copy(term,pos+2,length(term)-pos-1); exit; end; if search(term,'*',pos) then begin analysetmp:=mymult; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'/',pos) then begin analysetmp:=mydivid; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'and',pos) then begin analysetmp:=myand; st2:=copy(term,1,pos-1); st3:=copy(term,pos+3,length(term)-pos-2); exit; end; if search(term,'mod',pos) then begin analysetmp:=mymod; st2:=copy(term,1,pos-1); st3:=copy(term,pos+3,length(term)-pos-2); exit; end; if search(term,'div',pos) then begin analysetmp:=mydiv; st2:=copy(term,1,pos-1); st3:=copy(term,pos+3,length(term)-pos-2); exit; end; if search(term,'^',pos) then begin analysetmp:=mypower; st2:=copy(term,1,pos-1); st3:=copy(term,pos+1,length(term)-pos); exit; end; if search(term,'shl',pos) then begin analysetmp:=myshl; st2:=copy(term,1,pos-1); st3:=copy(term,pos+3,length(term)-pos-2); exit; end; if search(term,'shr',pos) then begin analysetmp:=myshr; st2:=copy(term,1,pos-1); st3:=copy(term,pos+3,length(term)-pos-2); exit; end; if copy(term,1,1)='(' then begin term:=copy(term,2,length(term)-2); goto start; end; if copy(term,1,3)='not' then begin analysetmp:=mynot; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,4)='sinc' then begin analysetmp:=mysinc; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,4)='sinh' then begin analysetmp:=mysinh; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,4)='cosh' then begin analysetmp:=mycosh; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,4)='tanh' then begin analysetmp:=mytanh; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,4)='coth' then begin analysetmp:=mycoth; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,3)='sin' then begin analysetmp:=mysin; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,3)='cos' then begin analysetmp:=mycos; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,3)='tan' then begin analysetmp:=mytan; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,3)='cot' then begin analysetmp:=mycot; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,4)='sqrt' then begin analysetmp:=mysqrt; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,3)='sqr' then begin analysetmp:=mysqr; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,7)='arcsinh' then begin analysetmp:=myarcsinh; st2:=copy(term,8,length(term)-7); st3:=''; exit; end; if copy(term,1,7)='arccosh' then begin analysetmp:=myarccosh; st2:=copy(term,8,length(term)-7); st3:=''; exit; end; if copy(term,1,7)='arctanh' then begin analysetmp:=myarctanh; st2:=copy(term,8,length(term)-7); st3:=''; exit; end; if copy(term,1,7)='arccoth' then begin analysetmp:=myarccoth; st2:=copy(term,8,length(term)-7); st3:=''; exit; end; if copy(term,1,6)='arcsin' then begin analysetmp:=myarcsin; st2:=copy(term,7,length(term)-6); st3:=''; exit; end; if copy(term,1,6)='arccos' then begin analysetmp:=myarccos; st2:=copy(term,7,length(term)-6); st3:=''; exit; end; if copy(term,1,6)='arctan' then begin analysetmp:=myarctan; st2:=copy(term,7,length(term)-6); st3:=''; exit; end; if copy(term,1,6)='arccot' then begin analysetmp:=myarccot; st2:=copy(term,7,length(term)-6); st3:=''; exit; end; if copy(term,1,5)='heavy' then begin analysetmp:=myheavy; st2:=copy(term,6,length(term)-5); st3:=''; exit; end; if copy(term,1,3)='sgn' then begin analysetmp:=mysgn; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,4)='frac' then begin analysetmp:=myfrac; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,3)='exp' then begin analysetmp:=myexp; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,3)='abs' then begin analysetmp:=myabs; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,5)='trunc' then begin analysetmp:=mytrunc; st2:=copy(term,6,length(term)-5); st3:=''; exit; end; if copy(term,1,2)='ln' then begin analysetmp:=myln; st2:=copy(term,3,length(term)-2); st3:=''; exit; end; if copy(term,1,3)='odd' then begin analysetmp:=myodd; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,4)='pred' then begin analysetmp:=mypred; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,4)='succ' then begin analysetmp:=mysucc; st2:=copy(term,5,length(term)-4); st3:=''; exit; end; if copy(term,1,5)='round' then begin analysetmp:=myround; st2:=copy(term,6,length(term)-5); st3:=''; exit; end; if copy(term,1,3)='int' then begin analysetmp:=myint; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if copy(term,1,3)='fac' then begin analysetmp:=myfac; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if term='rnd' then begin analysetmp:=myrnd; st2:=''; st3:=''; exit; end; if copy(term,1,3)='rnd' then begin analysetmp:=myrandom; st2:=copy(term,4,length(term)-3); st3:=''; exit; end; if term='x' then begin analysetmp:=myevalx; st2:=''; st3:=''; exit; end; if term='y' then begin analysetmp:=myevaly; st2:=''; st3:=''; exit; end; if term='z' then begin analysetmp:=myevalz; st2:=''; st3:=''; exit; end; if (term='pi') then begin analysetmp:=myid; str(pi,st2); st3:=''; exit; end; if term='e' then begin analysetmp:=myid; str(exp(1),st2); sst3:=''; exit; end; writeln(' ВНИМАНИЕ : НЕДЕКОДИРУЕМАЯ ФОРМУЛА '); analysetmp:=myid; st2:=''; st3:=''; end;

function evalobj.eval:real;
var tmpx,tmpy:real;
begin
if f1=nil then tmpx:=f1x else tmpx:=f1^.eval; if f2=nil then tmpy:=f2y else tmpy:=f2^.eval; eval:=f3(tmpx,tmpy); end;

function evalobj.eval1d(x:real):real;
begin
evalx:=x;
evaly:=0;
evalz:=0;
eval1d:=eval;
end;

function evalobj.eval2d(x,y:real):real;
begin
evalx:=x;
evaly:=y;
evalz:=0;
eval2d:=eval;
end;

function evalobj.eval3d(x,y,z:real):real;
begin
evalx:=x;
evaly:=y;
evalz:=z;
eval3d:=eval;
end;

constructor evalobj.init(st:string);
var st2,st3:string;
error:integer; begin
f1:=nil;
f2:=nil;
analyse(st,st2,st3);
f3:=analysetmp;
val(st2,f1x,error);
if st2='' then
begin
f1x:=0; error:=0; end;
if error<>0 then
new (f1,init(st2)); val(st3,f2y,error);
if st3='' then
begin
f2y:=0; error:=0; end;
if error<>0 then
new (f2,init(st3)); end;

destructor evalobj.done;
begin
if f1<>nil then
dispose(f1,done); if f2<>nil then
dispose(f2,done); end;

end.

[000159]



Содержание раздела