# Accuracy of float numbers
**URL:** https://discourse.processing.org/t/accuracy-of-float-numbers/22096
**Category:** Coding Questions
**Created:** [June 23, 2020, 2:06pm UTC](https://discourse.processing.org/t/accuracy-of-float-numbers/22096 "2020-06-23T14:06:47Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@paulstgeorge](https://discourse.processing.org/u/paulstgeorge)
#### Post date: [June 23, 2020, 2:06pm UTC](https://discourse.processing.org/t/accuracy-of-float-numbers/22096/1 "2020-06-23T14:06:47Z")
The map function should produce a float (see code below). If one looks at the first 10 results, with i first and then i mapped between 85.0 and 170.0, we have:
85 85.0
86 87.0
87 89.0
88 91.0
89 93.0
90 95.0
91 97.0
92 99.0
93 101.0
94 103.0
BUT by my calculations, we should have:
85 85.0000
86 87.0060
87 88.9950
88 91.0010
89 93.0070
90 94.9960
91 97.0020
92 99.0080
93 100.9970
94 103.0030
How do I get the more accurate result? I have tried workarounds such as converting to string and then converting back to float.
```auto
float threshold1 = 85.0;
float threshold2 = 170.0; // threshold2 > threshold1
void setup() {
}
void draw() {
for (int i = 85; i < 170; i++ ) {
float m = map(i, threshold1, threshold2, threshold1, 255.0);
//
println(i, m); // error checking
}
exit();
}
```
@kll @GoToLoop @jeremydouglass
---
### Author:  [@jeremydouglass](https://discourse.processing.org/u/jeremydouglass)
#### Post date: [June 23, 2020, 3:05pm UTC](https://discourse.processing.org/t/accuracy-of-float-numbers/22096/2 "2020-06-23T15:05:47Z")
> [@paulstgeorge](#):
>
> BUT by my calculations, we should have:
I’m not understanding this.
For ever step that your input (85-170) increases, your output (85-255) should increase by 2, because that is the ratio between the two ranges:
(255-85) / (170-85) = 2.0
170 / 85 = 2.0
2 / 1 = 2.0
That means only integer answers.
85 85
86 87
87 89
Am I misunderstanding?
---
### Author:  [@quark](https://discourse.processing.org/u/quark)
#### Post date: [June 23, 2020, 5:10pm UTC](https://discourse.processing.org/t/accuracy-of-float-numbers/22096/3 "2020-06-23T17:10:58Z")
You calculations are wrong take `i = 94` we get
Parametric position in first range t = (94-85)/(170 - 85) = 0.1058823529
The value in the new range is v = 85 + t \* (255-85) = 103
It is _not_ 103.0030 as you claim - the computer is right. 😌
---
### Author:  [@paulstgeorge](https://discourse.processing.org/u/paulstgeorge)
#### Post date: [June 23, 2020, 5:12pm UTC](https://discourse.processing.org/t/accuracy-of-float-numbers/22096/4 "2020-06-23T17:12:44Z")
Ah, so that’s how map() works. Thank you for the very clear explanation. My calculations were wrong so my expectations were wrong