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+--- Thread: [Help: CAS Code] Comparing exact with approx expressions (/thread-7173.html)
[Help: CAS Code] Comparing exact with approx expressions - compsystems - 11-05-2016 02:57 PM
I want to print in the terminal window, a numeric or symbolic value, depending on whether, is the same or different in their approximate or exact value, to avoid print two the same result. For this I am writing a program that compares two expressions exactSameApprox(expr1, expr2)
PHP Code:
#cas
exactSameApprox(expr1, expr2):=
begin
//print(delDot(expr1) == delDot(expr2)); wait();
if eq(delDot(expr1),delDot(expr2)) == true then
return true;
else
return false;
end;
end;
delDot( mExpr ):=
begin
local exprStr := string( mExpr );
if fp( approx( mExpr ) ) == 0 then
exprStr:= left(exprStr, instring(exprStr,".")-1); // the decimal dot is deleted when the fractional part is zero
end;
return exprStr;
end;
#end
terms
1: If the approximate value is the same that exact return "TRUE"
exactSameApprox(5, 5) -> true
"5" same "5" -> true
numbers with fractional part == 0, are considered equals, it requires a function to remove the fractional part delDot( mExpr )
exactSameApprox(1, 1.0) -> true or
exactSameApprox(1, 1.) -> true or
exactSameApprox(1.0, 1) -> true or
1.0 -> 1
"1" same "1" -> true
2: if the exact value is different from the approximate value must be return FALSE, BUT MY CODE FAILS.
exactSameApprox(2, 4/2) -> true // FAIL =( must be return FALSE
"2" same "4/2" -> false
Who can help me improve the code above?
the problem is that when storing, or convert to string a mathematical expression, this first is evaluated.
Using QUOTE (not to recall the argument of the input arg) to convert string =(
PHP Code:
deldot(mexpr):=
begin
local exprstr:= string( quote(mexpr) ); // -> exprstr:=" 'mexpr' " and not 'rcl(mexpr)',
Thanks
RE: [Help: CAS Code] Comparing exact with approx expressions - compsystems - 11-05-2016 08:39 PM
sorry for my bad English
expr0:=4/2 [enter] 2 ok
string(expr0) [enter] "2" ok
expr1:=quote(4/2) [enter] 4/2 ok
string(expr1) [enter] "2" =( I want to display as "4/2"
now
string(eval(var1,1)) [enter] "4/2" ok =) but within a program, how I make so that the entry is stored as quote?
PHP Code:
compare1(expr1, expr2):=
begin
local str1:= string(eval(expr1,1));
local str2:= string(eval(expr2,1));
local rtn;
print();
print(str1); wait();
print(str2); wait();
if eq(str1,str2) then
rtn:= true;
else
rtn:= false;
end;
print(rtn); wait();
return rtn;
end;
compare1(2,4/2) true =(
compare1('2','4/2') false =) but forcing the entry as '' the idea is that the program will become ''
I think that an object between single quotes '' must be stored as such and not evaluate it, otherwise the QUOTE command has not purpose, are you agree?
expr2:='4/2'
type(expr2) -> DOM_QUOTEDEXPR // without evaluate
RE: [Help: CAS Code] Comparing exact with approx expressions - CH3791 - 11-05-2016 11:27 PM
(11-05-2016 08:39 PM)compsystems Wrote: I think that an object between single quotes '' must be stored as such and not evaluate it, otherwise the QUOTE command has not purpose, are you agree?This is a very good proposal. However, one thing I don't understand is your use of two arguments for the eval command eg. string(eval(expr1,1)). None of the documentation or manuals state anything about what a second argument will do.
EDIT: Oops, I see you've already discussed it here. http://www.hpmuseum.org/forum/thread-7162.html