I am implementing the CORDIC algorithm for the sin
trigonometric function. In order to do this, I need to hardcode/calculate a bunch of arctangent values. Right now my function seems to work (as validated by Wolfram Alpha) to the precision that is printed, but I would like to be able to print all 32 bits of precision of my f32
. How may I do that?
fn generate_table() {
let pi: f32 = 3.1415926536897932384626;
let k1: f32 = 0.6072529350088812561694; // 1/k
let num_bits: uint = 32;
let num_elms: uint = num_bits;
let mul: uint = 1 << (num_bits - 2);
println!("Cordic sin in rust");
println!("num bits {}", num_bits);
println!("pi is {}", pi);
println!("k1 is {}", k1);
let shift: f32 = 2.0;
for ii in range(0, num_bits) {
let ipow: f32 = 1.0 / shift.powi(ii as i32);
let cur: f32 = ipow.atan();
println!("table values {}", cur);
}
}
Use the precision format specifier; a .
followed by the number of decimal points of precision you'd like to see:
fn main() {
let pi: f32 = 3.1415926536897932384626;
let k1: f32 = 0.6072529350088812561694; // 1/k
println!("pi is {:.32}", pi);
println!("k1 is {:.32}", k1);
}
I chose 32, which is more than the number of decimal points in either of these f32
s.
pi is 3.14159274101257324218750000000000
k1 is 0.60725295543670654296875000000000
Note that the values no longer match up; floating point values are difficult! As mentioned in a comment, you may wish to print as hexadecimal or even use your literals as hexadecimal.