Float.kt

import java.math.RoundingMode
import kotlin.math.round

/**
 * Created by rodrigosimoesrosa.
 */
const val DIGITS = 1

fun Float.round(decimals: Int = DIGITS): Float {
    var multiplier = 1.0f
    repeat(decimals) { multiplier *= 10 }
    return round(this * multiplier) / multiplier
}

fun Float.roundCeiling(digits: Int = DIGITS): Float {
    return toBigDecimal().setScale(digits, RoundingMode.CEILING).toFloat()
}

fun Float.roundFloor(digits: Int = DIGITS): Float {
    return toBigDecimal().setScale(digits, RoundingMode.FLOOR).toFloat()
}

fun Float.roundHalfEven(digits: Int = DIGITS): Float {
    return toBigDecimal().setScale(digits, RoundingMode.HALF_EVEN).toFloat()
}

fun Float.roundHalfDown(digits: Int = DIGITS): Float {
    return toBigDecimal().setScale(digits, RoundingMode.HALF_DOWN).toFloat()
}

infix fun ClosedRange<Float>.step(step: Float): Iterable<Float> {
    require(start.isFinite())
    require(endInclusive.isFinite())
    require(step.round() > 0.0) { "Step must be positive, was: $step." }
    require(start != endInclusive) { "start and endInclusive must not be the same" }

    if (endInclusive > start) {
        return generateSequence(start) { previous ->
            if (previous == Float.POSITIVE_INFINITY) return@generateSequence null
            val next = previous + step.round()
            if (next > endInclusive) null else next.round()
        }.asIterable()
    }

    return generateSequence(start) { previous ->
        if (previous == Float.NEGATIVE_INFINITY) return@generateSequence null
        val next = previous - step.round()
        if (next < endInclusive) null else next.round()
    }.asIterable()
}

(1.0f .. 0.0f).step(.1f).forEach { System.out.println("value: $it") }
output:
value: 1.0
value: 0.9
value: 0.8
value: 0.7
value: 0.6
value: 0.5
value: 0.4
value: 0.3
value: 0.2
value: 0.1
value: 0.0

(0.0f .. 1.0f).step(.1f).forEach { System.out.println("value: $it") }
output:
value: 0.0
value: 0.1
value: 0.2
value: 0.3
value: 0.4
value: 0.5
value: 0.6
value: 0.7
value: 0.8
value: 0.9
value: 1.0