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Why does floating-point arithmetic not give exact results when adding decimal fractions?
(31 answers)
Closed 7 years ago.
The value of d which is a double when compared to 0.01 is not satisfied due to presence of some digits at the end of the number which I found using flags . Why does this occur and how do we overcome this ? Thank you .
Code for this : http://i.stack.imgur.com/06I81.png
if ( abs( d - 0.01 ) < 0.0000001 ) ...
Related
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Round double to 3 points decimal [duplicate]
(4 answers)
Closed 4 months ago.
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With a function, I'm getting these values.. 0.07, 0.038, 0.072, 0.078. Now, I'm trying to apply round of to these values so that they should return like this.
round(val, decimal_place). So that, 0.038 value should return as 0 and rest should come as 0.1. (I can do it using an if condition like limiting with <0.5>. But, want to know. Is there any such function is there in C++ which limit decimal places below 0.5.
It's there in VB by doing like this I think. roundof(value, decimal_place).
You can use setprecision() to limit the decimal place on floating point numbers.
var = 1.0 / 3.0; // returns 0.33333333...
cout << fixed << setprecision(1) << var; // returns 0.3
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Assigning a lower precision number to a higher precision in Fortran90
(1 answer)
Numerical Precision in Fortran 95:
(2 answers)
Closed 4 years ago.
I'm trying to understand the difference between these two:
REAL*8 X
X=1.5D0
WRITE(6,*) (0.6D0 + (2*x)/5.)
WRITE(6,*) (0.6 + (2*x)/5.D0)
I would expect them to give identical results, but I get instead
1.2000000000000000
1.2000000238418580
Why is 0.6 not cast to double precision in the second case even if it is supposed to be summed to a value in double precision? What is happening?
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Floating point inaccuracy examples
(7 answers)
exact representation of floating points in c
(9 answers)
Closed 8 years ago.
As the title states, I'd like to start from 1 and decrement with by 0.01 all the way down to zero.
Problem is, I'm using floats and I keep getting values such as 0.5000000001.
Simply use an int, Start at 100 decrement down to 0 and divide the value by 100.0
for (int i=100; i>=0; --i)
{
float f = i/100.0f;
...
}
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Division result is always zero [duplicate]
(4 answers)
Closed 9 years ago.
I am doing the following
float years = (1/31536000) * 883102.00;
and I get years = 0000000
while the actual answer is 0.0.28
Any suggestion on what might be going wrong ?
You should instead do
float years = (1.0/31536000.0) * 883102.00;
or
float years = (1.0/31536000) * 883102.00;
might work as well. Your very first number is treated as integer.
Just do
float years = 883102.00/31536000;
This will save computation.
Since you are diving 1 by something and then multiplying.
Alternatively just set 1 to 1.00
1 is an int. The compiler then assumes that you are interested in working in ints and then 1/3153600 becomes 0. Just add a .0 to the 1 and your calc should work.
float years = (1.0/31536000) * 883102.00;
That first term is being cast as an int, and thus is being rounded to 0. Try this:
float years = (1.00 / 31536000.00) * 883102.00
(1/31536000) will yield 0 that multiplied by any number would be 0.
Make atleast one of numerator or denominator float (like 1.0 or 31536000.0)
883102.0 / 31536000 will do just what you want.
Because of the Integer-Division
(1/31536000)
the fractional digits get truncate and the result is "zero".
You have to add a dot:
(1.0/31536000.0) or (1./31536000.)
This question already has answers here:
Closed 12 years ago.
Possible Duplicate:
Incorrect floating point math?
Using C++ console app in visual studio.
float percentCorrect;
percentCorrect = ( 7 / 5 );
printf("%f", percentCorrect);
output is 1.0000
OK so how do I get the correct decimal output??
7 and 5 are integers, so the compiler treats them as such and does integer division.
float percentCorrect;
percentCorrect = (7.0/5.0);
printf("%f", percentCorrect);
The above should print out the expected value.
You need to include a decimal: 7.0/5.0
7 and 5 are integer literals, so 7 / 5 performs integer division.
You need to have at least one floating literal for floating-point division to be performed:
float percentCorrect = 7.0 / 5.0;