Install Separatrix on a Mac

This guide takes you from the download to your first project. One file works on every Mac, with Apple silicon (M1 and later) or with an Intel processor. Separatrix needs no internet connection after you install it.

The steps match macOS 15 Sequoia and newer. Older versions differ only at first launch, and the first-launch section says how.

Download the file

Go to the Separatrix releases page and look under Assets. Download these two files:

• Separatrix_1.0.1_macos_universal.dmg, the disk image that holds the app.
• SHA256SUMS.txt, the list of checksums you use to check the download.

Both land in your Downloads folder. The names on this page are for version 1.0.1. A newer release has its own number in each name.

Check the download

SHA256SUMS.txt lists the SHA-256 checksum of every file in the release. If your file's checksum matches, the download is complete and is the file that was published.

1. Open Terminal. It is in Applications, in the Utilities folder.

2. Run this command:

   cd ~/Downloads && shasum -a 256 Separatrix_1.0.1_macos_universal.dmg

   Terminal prints a line of 64 letters and digits, then the file name.

3. Run this command to show the published checksum:

   grep macos_universal.dmg SHA256SUMS.txt

4. Compare the two lines of 64 characters. They must be identical.

If they differ, delete the file and download it again. Do not open a file that fails the check.

Install it

1. Double-click Separatrix_1.0.1_macos_universal.dmg in Downloads. A window opens with the Separatrix icon and the Applications folder.
2. Drag the Separatrix icon onto the Applications folder.
3. Close the window. In the Finder sidebar, click the eject button beside Separatrix to eject the disk image.

Start Separatrix for the first time

Separatrix 1.0.1 and later are signed by their developer and notarized by Apple, so macOS knows where the app comes from and that Apple checked it.

1. Open Applications and double-click Separatrix.

2. macOS asks whether you are sure you want to open an app downloaded from the internet. Click Open.

macOS asks only this first time.

Separatrix 1.0.0 is not notarized, and macOS blocks it the first time you open it. If you have 1.0.0, follow the steps for 1.0.0, or download the latest version instead.

Separatrix opens on a gallery of example systems from Strogatz's Nonlinear Dynamics and Chaos. Click any card to start from that system. The Linux guide has a picture of the gallery. It looks the same on a Mac.

If you have Separatrix 1.0.0

Version 1.0.0 is not notarized by Apple, so macOS blocks it the first time you open it. You allow it once, and after that it opens like any other app.

1. Open Applications and double-click Separatrix. macOS shows a dialog titled "Separatrix" Not Opened. Click Done.

2. Open the Apple menu and choose System Settings.

3. Click Privacy & Security in the sidebar.

4. Scroll down to the Security section. It says "Separatrix" was blocked to protect your Mac. Click Open Anyway.

5. Type your login password, or use Touch ID, and click OK.

6. macOS asks one last time whether to open Separatrix. Click Open.

Open Anyway stays available for about an hour after step 1. If it is gone, double-click Separatrix again and repeat the steps.

On macOS 14 Sonoma or older, there is a shorter way. Control-click Separatrix in Applications, choose Open, then click Open in the dialog.

If macOS says Separatrix is damaged

If macOS says "Separatrix" is damaged and can't be opened, or, with version 1.0.0, Open Anyway never appears, remove the quarantine flag that macOS put on the download:

1. Open Terminal.

2. Run this command:

   xattr -dr com.apple.quarantine /Applications/Separatrix.app

3. Double-click Separatrix in Applications again.

The command changes only the Separatrix app. It does not turn off any protection for other apps.

Open a project

Separatrix saves projects as .sepx files. You can open one in four ways:

• Click Open… at the top right of the gallery, or press ⌘O at any time, then choose the file.
• Drag a .sepx file from the Finder onto the Separatrix window.
• Drag a .sepx file onto the Separatrix icon in the Dock.
• Double-click a .sepx file in the Finder.

The project opens with its equations, trajectories and view as they were saved. The gallery also lists the projects you opened most recently under Recent. Click one to open it again.

Update Separatrix

Separatrix 1.0.0 cannot update itself. If you have 1.0.0, install the latest version once by following this guide from the top. From 1.0.1 on, updates install themselves.

Separatrix checks for a new version after it starts. When one exists, the status bar at the bottom of the window shows Update available beside the version number, such as v1.0.1.

1. Click the version number. You can also choose Separatrix > Check for Updates… in the menu bar at any time.
2. Click Install and restart.

Uninstall Separatrix

1. Quit Separatrix.
2. Open Applications and drag Separatrix to the Trash.

Uninstalling keeps your .sepx projects. To also delete the list of recent projects, delete the folder ~/Library/Application Support/io.github.uncrayon.separatrix.