all — Test whether all elements are nonzero along a dimension in MATLAB and RunMat.
all(X) returns logical true when every element in the selected slice of X is nonzero. By default, all reduces along the first non-singleton dimension; dim, vecdim, and "all" follow the MATLAB-compatible contract, while explicit nanflag arguments are available only in RunMat mode.
Syntax
B = all(A)
B = all(A, dim)
B = all(A, "all")
B = all(A, nanflag)
B = all(A, dim, nanflag)
B = all(A, nanflag, dim)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
A | Any | Yes | — | Input array. |
dim | Any | No | [] | Dimension selector or vector of dimensions. |
all | StringScalar | No | "all" | Reduce across all dimensions. |
nanflag | StringScalar | No | "includenan" | NaN handling mode: "includenan" or "omitnan". |
Returns
| Name | Type | Description |
|---|---|---|
B | LogicalArray | Logical reduction result. |
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:all:InvalidArgument | Dimension/all/nanflag argument grammar is invalid. | all: invalid reduction argument specification |
RunMat:all:InvalidInput | Input type is unsupported for all reduction. | all: unsupported input type |
RunMat:all:Internal | Reduction execution fails due to internal conversion, provider, or shape operations. | all: internal reduction failure |
How all works
- Works with logical, numeric, complex, and character arrays; other types raise a descriptive error.
- Accepts
all(X, dim)to reduce along a single dimension orall(X, vecdim)to collapse multiple axes at once. all(X, 'all')flattens the entire array into a single logical scalar.- Typed integer data and integer
dimorvecdimselectors accept all eight built-in integer classes and always return logical results. - RunMat mode adds explicit
all(___, 'omitnan')andall(___, 'includenan')forms; MATLAB-compatible modes reject those flags. - Without an explicit flag,
NaNcounts as nonzero. - Empty dimensions yield logical ones with MATLAB-compatible shapes; empty arrays reduced with
'all'returntrue. - Results are always host-resident logical scalars or logical arrays, even when the input tensor lives on the GPU, because the runtime copies the compact output back to the CPU.
Does RunMat run all on the GPU?
RunMat Accelerate keeps inputs resident on the GPU whenever possible. Providers that expose reduce_all_dim (and optionally reduce_all) perform the AND-reduction on device buffers, and the runtime then downloads the tiny logical result back to the CPU. When those hooks are missing, RunMat gathers the input tensor and evaluates the reduction on the host instead, preserving MATLAB behaviour in all cases.
GPU memory and residency
You usually do not need to call gpuArray manually. The fusion planner keeps GPU-resident inputs on the device and only gathers the small logical results that all produces. If your workload already uses explicit gpuArray/gather calls for MATLAB compatibility, RunMat honours them and still produces correct logical outputs.
Examples
Checking if every column is nonzero
A = [1 2 3; 4 5 6];
colAllNonZero = all(A)Expected output:
colAllNonZero = [1 1 1]Verifying that each row contains only nonzero values
B = [1 0 3; 4 5 6; 0 7 8];
rowAllNonZero = all(B, 2)Expected output:
rowAllNonZero = [0; 1; 0]Collapsing multiple dimensions with vecdim
C = reshape(1:24, [3 4 2]);
allAlongDims = reshape(all(C > 0, [1 2]), 1, 2)Expected output:
1 1Reducing all elements to a single logical scalar
D = [2 4; 6 8];
everythingNonZero = all(D, 'all')Expected output:
everythingNonZero = trueObserving the default NaN behavior
E = [NaN 1 2; NaN 0 3];
everyValue = all(E);
disp(everyValue)Expected output:
1 0 1Evaluating all on GPU arrays
G = gpuArray([1 1 1; 1 1 1]);
gpuResult = all(G, 2); % RunMat returns a host logical array
disp(gpuResult)Expected output:
1
1Testing all with character arrays
chars = ['a' 0 'c'];
allPrintable = all(chars);
disp(allPrintable)Expected output:
0Using all with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how all changes the result.
Run a small all example, explain the result, then change one input and compare the output.
FAQ
When should I use the all function?⌄
Use all whenever you need to confirm that every element of an array, row, column, or sub-array is nonzero or logical true.
Does all always return logical values?⌄
Yes. Results are logical scalars or logical arrays even when the computation involves GPU inputs.
How do I test a specific dimension?⌄
Pass the dimension as the second argument (for example, all(X, 2) reduces each row). Provide a vector such as [1 3] to collapse multiple axes.
What does all(X, 'all') compute?⌄
It reduces across every dimension of X and returns a single logical scalar indicating whether every element of the entire array is nonzero.
How are NaN values handled?⌄
By default they count as nonzero. RunMat mode additionally accepts explicit 'omitnan' and 'includenan' flags; MATLAB-compatible modes reject those extension forms.
Does all work with complex numbers?⌄
Yes. Complex values are considered nonzero when either the real or imaginary component is nonzero. Complex values containing NaN obey the 'omitnan'/'includenan' rules.
Can I apply all to character arrays?⌄
Yes. Characters compare against their Unicode code points; zero-valued code points are treated as false, and everything else is true.
What happens with empty inputs?⌄
Empty reductions follow MATLAB semantics: dimensions of length zero produce logical ones, while all(X, 'all') over an empty array evaluates to true.
How do GPU backends accelerate all?⌄
Providers may expose specialised AND-reduction kernels (reduce_all_dim, reduce_all) or use fused_reduction to remain on the device. When such hooks are absent, RunMat downloads the small output and computes on the host.
Related Math functions
Reduction
any · bounds · cummax · cummin · cumprod · cumsum · cumtrapz · diff · gradient · max · maxk · mean · median · min · mink · movmax · movmean · movmedian · movmin · movprod · movstd · movsum · movvar · nnz · prod · rms · std · sum · trapz · var
Elementwise
abs · angle · bsxfun · complex · conj · double · erf · erfcinv · exp · expm1 · factorial · flintmax · gamma · gammaln · heaviside · hypot · idivide · imag · intmax · intmin · ldivide · log · log10 · log1p · log2 · minus · nextpow2 · plus · pow2 · power · rdivide · real · realmax · realmin · realsqrt · rescale · sign · single · sqrt · swapbytes · times · typecast · uint16 · uint32 · uint8
Trigonometry
acos · acosh · asin · asinh · atan · atan2 · atanh · cos · cosd · cosh · cospi · deg2rad · pol2cart · rad2deg · sin · sind · sinh · sinpi · tan · tand · tanh
Structure
bandwidth · isdiag · ishermitian · issymmetric · istril · istriu · symrcm
Signal
blackman · butter · buttord · cheb2ord · conv · conv2 · deconv · downsample · envelope · filter · filtfilt · fir1 · freqz · gauspuls · hamming · hann · hilbert · periodogram · pulstran · pwelch · rectpuls · resample · sawtooth · sinc · spectrogram · square · tripuls · unwrap · upsample · zplane
Optim
coneprog · fminbnd · fminunc · fsolve · fzero · integral · linprog · lsqcurvefit · lsqnonlin · optimoptions · optimset · quad · secondordercone
Ops
cross · ctranspose · dot · mldivide · mpower · mrdivide · mtimes · pagemtimes · pagetranspose · trace · transpose
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how all is executed, line by line, in Rust.
- View the source for all in Rust on GitHub
- Learn how the RunMat runtime works
- Found a bug? Open an issue with a minimal reproduction.
About RunMat
RunMat is an open-source runtime that executes MATLAB-syntax code blazing on any GPU. It is licensed under the Apache 2.0 license.
- RunMat automatically optimizes your math for GPU execution on Apple, Nvidia, and AMD hardware. No code changes needed. Simulations that took hours now take minutes.
- Start running code in seconds. RunMat runs in the browser, on the desktop, or from the CLI. No license server, no IT ticket.