Equation or not?

[Han]

I took the liberty of optimizing some of the programs above where I could. Basically, first three test whether or not to exclude <= and >= when searching for =. As EdDereDdE pointed out, these are really the only tests that are necessary. The last program converts all the equations, which can be time consuming when searching through a large list. The were renamed findeq, findeq2, findeq3, and findeq4 in the order that they were posted.

To test (even on the emulator), type: fetime(3000)

This will create a random list in L0 of size 3000 (you will need large lists to test on the emulator). Then each program is timed in the same manner. Use a smaller value on the actual calculator (e.g. 100)

Here is the "test kit":

PHP Code:

export randL0(k)
begin
  local j, n, m;
  local ineq:={ "=", "<", ">", "<=", ">=", "<>", "≠", "≤", "≥" };
  L0:={};

  for j from 1 to k do
    n:=ip(random*9)+1;
    m:=string(ip(random*9)+1,1,0);
    L0(0):=m + "x + " + m + "y" + ineq(n) + m; 
  end; 
end;

// *********************************
export findeq()
begin

local j,m,p;

m:=size(L0);
p:={};

for j from 1 to m do
  if instring(L0(j),">") OR instring(L0(j),"<") then continue; end;
  // now check for = symbol
  if instring(L0(j),"=") then p(0):=j; end;
end;

return(p);

end; 

// *********************************
export findeq2()
begin
L1:={"<",">"};
remove(0,IFTE(ΣLIST(EXECON("INSTRING(L0,&1)",L1))+NOT(INSTRING(L0,"=")),0,L0));
end;

// *********************************
export findeq3()
begin
LOCAL eq:="=",ls:="<",gt:=">";
RETURN CAS("
remove((x)→((INSTRING(x,gt))),
remove((x)→((INSTRING(x,ls))),
remove((x)→(0==(INSTRING(x,eq))),L0)
))
");
end;

// *********************************
EXPORT findeq4()
BEGIN
local m,p,j;

m:=size(L0);
p:={};

for j from 1 to m do

L0(j):=CAS.expr(L0(j));
IF (CAS.part(L0(j),0) == "==") THEN p:= CAS.Concat(p,j);END;

end;

return(p);

END; 

// *********************************
export fetime(k)
begin
  local t1, t2, t3, t4;
  randL0(k);

  // some programs modify L0
  L9:=L0;
  t1:=teval(findeq());

  L0:=L9;
  t2:=teval(findeq2());

  L0:=L9;
  t3:=teval(findeq3());

  L0:=L9;
  t4:=teval(findeq4());

  return({t1,t2,t3,t4});
end;