complex — Construct complex double values from real and imaginary parts.

z = complex(a, b) constructs a + 1i*b from real-valued inputs. z = complex(a) returns a using complex storage with a zero imaginary part, and existing complex inputs pass through unchanged.

How complex works

• With two inputs, a and b must be real numeric values. Complex inputs raise an error.
• Two non-scalar inputs must have the same size. If either input is scalar, it expands across the other input.
• Integer and logical inputs are promoted to double precision before constructing the complex result.
• String and character inputs are rejected because the constructor accepts numeric inputs only.
• Unary complex(a) preserves existing complex scalars and complex tensors. Real inputs become complex values with zero imaginary parts.
• Empty real tensors preserve their empty shape and return empty complex tensors.

How RunMat runs complex on the GPU

RunMat rejects gpuArray inputs for complex today because the active GPU providers expose real-valued tensor buffers, while this constructor creates complex storage. Native complex GPU residency can be added later without changing the public call forms.

GPU memory and residency

No. complex returns host-resident Value::Complex or Value::ComplexTensor values today. Use gather before construction if values are currently device-resident.

Examples

Constructing a complex scalar from real and imaginary parts

z = complex(3, 4)

Expected output:

z = 3+4i

Constructing a complex row vector from matching real arrays

re = [1 2 3];
im = [4 5 6];
z = complex(re, im)

Expected output:

z = [1+4i 2+5i 3+6i]

Expanding a scalar imaginary part across an array

re = [1 2 3];
z = complex(re, -1)

Expected output:

z = [1-1i 2-1i 3-1i]

Forcing complex storage with a zero imaginary part

z = complex(12);
tf = isreal(z)

Expected output:

z = 12+0i

tf =
     0

Leaving an existing complex value unchanged

z = complex(1 + 2i)

Expected output:

z = 1+2i

Rejecting non-scalar implicit expansion

z = complex([1 2 3], [10; 20])

Expected output:

error: complex: real and imaginary parts must have the same size, unless one input is scalar

FAQ

Related Math functions

Open-source implementation

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

• View complex.rs on GitHub
• Learn how the 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 — faster, on any GPU, with no license required.

• Simulations that took hours now take minutes. RunMat automatically optimizes your math for GPU execution on Apple, Nvidia, and AMD hardware. No code changes needed.
• Start running code in seconds. Open the browser sandbox or download a single binary. No license server, no IT ticket, no setup.
• A full development environment. GPU-accelerated 2D and 3D plotting, automatic versioning on every save, and a browser IDE you can share with a link.

Getting started · Benchmarks · Pricing