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Double Comparison

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Abhishek Mishra
49
Abhishek Mishra  

Hello

 

How we can compare double value ,when double value is nearly equal to zero?

Please Help. 

Carl Schreiber
6785
Carl Schreiber  

I am using things like this:

#define isZero(x) ((fabs(x) < 0.000000001)
whroeder1
15023
whroeder1  
Mideel
74
Mideel  
just like that
JD4
1101
JD4  
Standard numerical comparisons ( >, <, == (logical) <=, >=, and so on) should work.  If you are not getting enough precision with double, then I think you are stuck, because it is even higher precision than float, according to this page.
whroeder1
15023
whroeder1  

The problem has nothing to do with precision (float vs double.)

The comparators work fine. The problem is with the equals. Is the equality important?

If you code Bid > trigger, is it OK for that to be true when Bid and Trigger are the same price? If you code Bid >= trigger, is it OK for it to be true when Bid is slightly below Trigger because of round off?

//        1        2        3        4        5        6        7        8        9       10
double t=1/10.0 + 1/10.0 + 1/10.0 + 1/10.0 + 1/10.0 + 1/10.0 + 1/10.0 + 1/10.0 + 1/10.0 + 1/10.0;
Print(t,"=1.0?",t==0); // 0.9999999999999999=1.0?false
If neither can be true, the equality is important, and you must understand The == operand. - MQL4 forum You can NOT use NormalizeDouble because that will not work on metals, (point != ticksize,) and NormalizeDouble uses Digits.
if( Bid - trigger >  0          ) // Bid >  trigger or possibly Bid == trigger
if( Bid > trigger               ) // equivalent.

if( Bid - trigger >  ticksize/2 ) // Bid >  trigger
if( Bid - trigger > -ticksize/2 ) // Bid >= trigger
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