addpath — Add folders to the MATLAB/RunMat search path for function and script resolution.

addpath prepends or appends folders to the active search path used to resolve functions, scripts, classes, and data files. Changes apply immediately to the current session, with path ordering behavior matching MATLAB semantics.

Syntax

oldpath = addpath(folder1)
oldpath = addpath(folder1, folder2, ...)
oldpath = addpath(folder1, ..., position)
oldpath = addpath(folder1, ..., "-frozen")
oldpath = addpath(folder1, ..., position, "-frozen")

Inputs

Returns

Errors

How addpath works

• Folder arguments may be character vectors, string scalars, string arrays, or cell arrays of character vectors or strings. Multi-row char arrays contribute one folder per row (trailing padding is stripped).
• In runmat compatibility mode only, a one-row numeric tensor can encode one folder name as Unicode scalar values. MATLAB-compatible modes reject this convenience form; use a character vector or string scalar for portable code.
• MATLAB command form is supported for path-like arguments, including addpath ./SourceCode, addpath ../lib -end, and addpath ./src:../shared -frozen.
• Multiple folders can be passed in a single argument using the platform path separator (: on Linux/macOS, ; on Windows); this is compatible with genpath.
• By default, folders are added to the top of the search path. Use '-end' to append or '-begin' to force prepending explicitly. Only one position flag is permitted.
• The '-frozen' flag is accepted for MATLAB compatibility. RunMat does not currently track frozen entries separately; the flag simply suppresses incompatibility warnings.
• Duplicate entries are removed automatically so each folder appears at most once. On Windows, comparisons are case-insensitive.
• Inputs are resolved to absolute, canonicalised paths. Relative inputs are interpreted relative to the current working directory, and ~ expands to the user’s home directory.
• Folders must exist. RunMat raises addpath: folder '<name>' not found when a directory is missing or addpath: '<name>' is not a folder when the target is not a directory.

Does RunMat run addpath on the GPU?

addpath manipulates host-side configuration. Resident numeric character-code tensors are rejected in MATLAB-compatible modes before gather; admitted RunMat-extension inputs gather to the host before parsing. No acceleration provider hooks or kernels are involved.

GPU memory and residency

No. addpath operates entirely on CPU-side text and path state. A resident numeric character-code tensor is a mode-gated RunMat extension that gathers only after compatibility admission.

Examples

Add a single folder to the top of the search path

mkdir("util/toolbox");
oldPath = path();
addpath("util/toolbox");
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/util/toolbox

Add a relative folder with MATLAB command syntax

mkdir("SourceCode");
oldPath = path();
addpath ./SourceCode
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/SourceCode

Append folders to the end of the search path

mkdir("shared/filters");
mkdir("shared/signal");
oldPath = path();
dirs = ["shared/filters", "shared/signal"];
addpath(dirs, "-end");
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/shared/filters:/shared/signal

Use genpath output to add a folder tree

mkdir("third_party/toolchain");
mkdir("third_party/toolchain/bin");
oldPath = path();
toolchain = genpath("third_party/toolchain");
addpath(toolchain);
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/third_party/toolchain:/third_party/toolchain/bin

Add folders from a cell array

mkdir("src/algorithms");
mkdir("src/visualization");
oldPath = path();
folders = ["src/algorithms", "src/visualization"];
addpath(folders, "-begin");
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/src/algorithms:/src/visualization

Move an existing folder to the top of the search path

mkdir("src/algorithms");
oldPath = path();
addpath("src/algorithms");
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/src/algorithms

Accept the MATLAB -frozen flag

mkdir("vendor/hardware");
oldPath = path();
addpath("vendor/hardware", "-frozen");
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/vendor/hardware

Retrieve the previous path and restore it later

mkdir("analysis/utilities");
oldPath = path();
old = addpath("analysis/utilities");
newPath = path();
path(old);
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/analysis/utilities

Combine multiple options

mkdir("contrib");
mkdir("docs/examples");
oldPath = path();
addpath("contrib", "docs/examples", "-end", "-frozen");
newPath = path();
count = fprintf('%s %s\n', oldPath, newPath);

Expected output:

/contrib:/docs/examples

Using addpath with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how addpath changes the result.

FAQ

Related Io functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how addpath is executed, line by line, in Rust.

• View the source for addpath in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

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