lib/step.js
function step (pointsToEvaluate, functionValuesX, functionValuesY) {
  return help.makeItArrayIfItsNot(pointsToEvaluate).map(function (point) {
    return functionValuesY[help.findIntervalLeftBorderIndex(point, functionValuesX)]
  })
}
function step (pointsToEvaluate, functionValuesX, functionValuesY) {
  return help.makeItArrayIfItsNot(pointsToEvaluate).map(function (point) {
    return functionValuesY[help.findIntervalLeftBorderIndex(point, functionValuesX)]
  })
}
function step ( pointsToEvaluate , functionValuesX , functionValuesY ) { return help . makeItArrayIfItsNot ( pointsToEvaluate ) . map ( function ( point ) { return functionValuesY [ help . findIntervalLeftBorderIndex ( point , functionValuesX ) ] } ) }
Evaluates interpolating step function at the set of numbers
or at a single number

@param {Number|Array} pointsToEvaluate     number or set of numbers
for which step is calculated
@param {Array} functionValuesX             set of distinct x values
@param {Array} functionValuesY             set of distinct y=f(x) values
@returns {Array}
Evaluates interpolating step function at the set of numbers or at a single number