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Comments on Evaluate a single variable polynomial equation

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Evaluate a single variable polynomial equation

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Challenge

Given a list of n numbers and x, compute $a + bx^1 + cx^{2} + ... + zx^{n-1}$, where a is the first value in the list, b is the second, etc. n is at most 256 and at least 0. The input value(s) can be any 32-bit float

Input can be in any format of choice, as long as it is a list of numbers and x. (And this'll likely stay this way, even if input rules change over time)

Test inputs

[1.0], 182 -> 1
[1.0, 2.0], 4 -> 9
[2.5, 2.0], 0.5 -> 3.5
[1.0, 2.0, 3.0, 4.0], 1.5 -> 24.25

Example ungolfed program (Rust)

// dbg! is a logging function, prints the expression and it's output.
// Good for seeing what's happening

// Test setup
pub fn main() {
    let inp: &[f32] = &[1.0, 2.0, 3.0, 4.0];
    let x: f32 = 1.5;
    dbg!(evaluate_polynomial(inp, x)); // take inputs, print result	
}

// Actual challenge answer function
pub fn evaluate_polynomial(inp: &[f32], x: f32) -> f32 {
    let mut accum: f32 = 0.0;

    for (idx, val) in inp.iter().enumerate() {
        // x.pow(idx) * val
        accum += dbg!(x.powf(idx as f32) * val);
    }

    return accum;
}

code-golf math

posted almost 4 years ago

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3y ago by user‭

moony‭

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