Rainbow indicator

gistfile1.txt

//@version=6
indicator("BTC Rainbow Intercept", shorttitle="Rainbow c", overlay=false, max_lines_count=500)

// --- Inputs ---
slope = input.float(5.7, "Slope", step=0.0001, tooltip="Exponent of the power law: price = 10^(slope·log10(days) + intercept)")
src   = input.source(close, "Price source")
projMonths = input.int(4, "Projection horizon (months)", minval=1, maxval=24)
showFlat   = input.bool(true, "Show flat-price projection")
showShift  = input.bool(true, "Show shifted-price projection")
shiftPct   = input.float(-10.0, "Price shift %", step=0.5)
showPower  = input.bool(true, "Draw power line on price chart")
showBands  = input.bool(true, "Draw intercept bands on price chart")
bandWidth  = input.float(0.05, "Band width (intercept units)", minval=0.01, step=0.01, tooltip="0.1 ≈ ×1.26 above / ×0.79 below the power line")
useManualC = input.bool(false, "Manual intercept", tooltip="Off: power line anchors to the current derived intercept (passes through the latest close). On: uses the value below.")
manualC    = input.float(-16.6773, "Manual intercept value", step=0.01)

// --- Days since genesis block (Jan 3, 2009) ---
genesisTime = timestamp("GMT", 2009, 1, 3, 0, 0)
daysSinceGenesis = (time - genesisTime) / 86400000.0

// --- First bar time (full chart anchor) ---
var float firstBarTime = na
if barstate.isfirst
    firstBarTime := time

// --- Implied intercept for the current price ---
intercept = math.log10(src) - slope * math.log10(daysSinceGenesis)

plot(intercept, "Implied intercept", color=color.orange, linewidth=2)
hline(-16.6773, "Fitted intercept (-16.6773)", color=color.gray, linestyle=hline.style_dashed)

// --- Projections (in the pane) ---
var array<line> projLines = array.new<line>()

drawProjection(float p0, float p1, color col) =>
    int   nSegs     = 16
    float horizonMs = projMonths * 30.4375 * 86400000.0
    float stepMs    = horizonMs / nSegs
    for i = 0 to nSegs - 1
        t1 = time + i * stepMs
        t2 = time + (i + 1) * stepMs
        d1 = (t1 - genesisTime) / 86400000.0
        d2 = (t2 - genesisTime) / 86400000.0
        pA = p0 + (p1 - p0) * i / nSegs
        pB = p0 + (p1 - p0) * (i + 1) / nSegs
        c1 = math.log10(pA) - slope * math.log10(d1)
        c2 = math.log10(pB) - slope * math.log10(d2)
        array.push(projLines, line.new(int(t1), c1, int(t2), c2,
             xloc = xloc.bar_time, color = col,
             style = line.style_dashed, width = 1))

// --- Power curves drawn on the MAIN price chart, spanning the full chart ---
var array<line> powerLines = array.new<line>()

drawPowerCurve(float c, color col, string sty) =>
    float dStart = (firstBarTime - genesisTime) / 86400000.0
    float dEnd   = daysSinceGenesis + projMonths * 30.4375
    int   nSegs  = 120
    float ratio  = math.pow(dEnd / dStart, 1.0 / nSegs)
    for i = 0 to nSegs - 1
        d1 = dStart * math.pow(ratio, i)
        d2 = dStart * math.pow(ratio, i + 1)
        t1 = genesisTime + d1 * 86400000.0
        t2 = genesisTime + d2 * 86400000.0
        p1 = math.pow(10, slope * math.log10(d1) + c)
        p2 = math.pow(10, slope * math.log10(d2) + c)
        array.push(powerLines, line.new(int(t1), p1, int(t2), p2,
             xloc = xloc.bar_time, color = col,
             style = sty, width = 1,
             force_overlay = true))

if barstate.islast
    while array.size(projLines) > 0
        line.delete(array.pop(projLines))
    while array.size(powerLines) > 0
        line.delete(array.pop(powerLines))

    if showFlat
        drawProjection(src, src, color.new(color.orange, 30))
    if showShift
        pShift = src * (1 + shiftPct / 100.0)
        drawProjection(pShift, pShift, color.new(color.red, 30))

    // choose intercept for the power line: auto (current derived) or manual
    float powerC = useManualC ? manualC : intercept

    if showPower
        drawPowerCurve(powerC, color.new(color.blue, 20), line.style_solid)
    if showBands
        drawPowerCurve(powerC + bandWidth, color.new(color.blue, 60), line.style_dotted)
        drawPowerCurve(powerC - bandWidth, color.new(color.blue, 60), line.style_dotted)