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Mandelbrot Deep Zoom Explorer

Zoom into the Mandelbrot set far past ordinary number precision, and watch each view sharpen as the calculation continues.

Loading the explorer…

Loading the explorer…

Drag to pan. Tap or click the image, then scroll or double click to zoom toward a point. On touch screens, drag with one finger and pinch with two. With the image focused, arrow keys pan, + and − zoom, and R returns to the overview.

Advanced

Auto uses the GPU when the device passes its start-up check, and the CPU otherwise.

Reuses nearby reference calculations after small moves. Leave this on unless you are comparing results.

Exact coordinates
GPU experiments

These only affect the GPU renderer. Changes are saved on this device and apply after a reload.

CPU workers that fix the few pixels the GPU cannot finish, in parallel. Devices with 8 or more cores use 4 by default.

Fast uses native 32-bit floating point, like other deep zoom programs, and is several times quicker. In very busy areas single pixels can differ slightly from the exact result. Exact uses slower 72-bit arithmetic with a checked error bound. In both, dark points reached the iteration budget and are not proven inside. The diagnostics below name the arithmetic in use.

Shows a quarter-resolution image within a moment, then fills in full detail. On by default.

Experimental. Sends GPU work in fewer batches. Measured results were mixed.

Experimental. Updates the image once per display frame. Measured results were mixed.

Experimental. Reads fewer shortcut tables per step. Measured results were mixed.

Experimental. Uses a cheaper size check where it is proven safe. Measured results were mixed.

Experimental. Tests for escape with a quick check first. Measured results were mixed.

Experimental. Changes the amount of work per GPU batch as it runs. Measured results were mixed.

Leave blank for the default of 512 (measured fastest at explorer sizes). Navigation gestures use 32 for quick cancellation.

Diagnostics

No calculation yet.

Places to visit

Each link opens that view in the explorer above. Shallow locations finish in seconds. Deep locations need many more calculations per pixel and can take minutes.

The whole set

The main heart-shaped body is the cardioid. The round shapes attached to it are bulbs. All the detail lives on the boundary between the coloured outside and the dark inside.

What to notice: pick any edge and zoom in. Smooth areas stay smooth, edges keep producing new shapes.

Open the whole set

Seahorse Valley

The narrow gap between the main cardioid and the large bulb on its left.

What to notice: curled tails that look like seahorses, lined up along both sides of the valley.

Open Seahorse Valley

Elephant Valley

The gap on the right side of the main cardioid, near its cusp.

What to notice: rows of thick trunk shapes that curl inward. Compare them with the thinner Seahorse Valley tails.

Open Elephant Valley

Real-axis antenna

The thin spike that runs left from the main body along the real axis.

What to notice: a small copy of the whole set sits on the antenna. The thin threads that connect it can vanish at low detail, so raise Detail if the copy looks isolated.

Open the antenna

Seahorse spirals

A closer view inside Seahorse Valley.

What to notice: double spirals that wind into a centre point, with smaller spirals branching off their arms.

Open the spirals

Period-doubling boundary

The point where the large left bulb meets the next smaller bulb on the real axis.

What to notice: each bulb along the axis is smaller than the last. Points in each one settle into a cycle twice as long as the one before.

Open the boundary

Deep: 10¹¹³ magnification

A published deep location from the rust-fractal project, near the antenna. It uses a budget of 35,494 iterations.

What to notice: filaments and spirals much like those near the surface, at a scale far below what ordinary 64-bit numbers can represent.

Open the 10¹¹³ view

Deep: 10³¹⁸ magnification

A published deep location from the rust-fractal project, near the top of the set. It uses a budget of 212,138 iterations.

What to notice: how long it takes. Most pixels need over a hundred thousand steps, so expect the image to fill in slowly.

Open the 10³¹⁸ view

Deep: 10¹⁰⁰⁰ magnification

A published deep location from the rust-fractal project, on the far left antenna. Its centre is written with over a thousand digits.

What to notice: the structure still looks like the Mandelbrot set. Use Back to return to the surface.

Open the 10¹⁰⁰⁰ view

Reading the image

Shapes

Each pixel is a number c. The explorer repeats z² + c from zero and counts the steps until the value grows past a fixed size. Points that never grow belong to the set. The boundary between the two is where the spirals, valleys and small copies of the whole set appear.

Colours

Colour shows how many steps a point took to escape. Bands close together mean the escape speed changes quickly, which happens near the boundary. Changing the palette recolours the finished pixels without calculating them again.

Dark, grey and pink pixels

Dark pixels did not escape within the chosen Detail budget. They may be inside the set, or they may need more steps. Raise Detail to find out. Grey pixels are still being calculated. A few pixels need a slower, more precise check because the fast calculation was not accurate enough there. On the GPU they show an estimated colour until the check finishes; on the processor they are pale pink. Both usually clear within moments.

How far can you zoom?

Ordinary 64-bit numbers run out of precision after about 10¹⁴ magnification. This explorer keeps exact decimal coordinates and uses high-precision reference points, so it can go much deeper. The practical limit is time: deeper views need more steps per pixel and more reference work. Auto uses the GPU when the device passes a start-up check. On our test machine the GPU finished every test view faster than the processor, by 25% to many times over. If a view cannot be finished on the GPU, the processor takes over.

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