trussx 0.2.0

Utilities for designing and analyzing truss structures
Documentation 
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[![Crates.io](https://img.shields.io/crates/v/trussx.svg)](https://crates.io/crates/trussx)
[![docs.rs](https://docs.rs/trussx/badge.svg)](https://docs.rs/trussx)

# trussx

Utilities for building and analysing pin-jointed truss structures. The crate provides a
small, strongly-typed API for creating joints and members, applying loads and supports,
and running a linear elastic analysis in three dimensions.

## Installation

Add the dependency to your `Cargo.toml`:

```toml
[dependencies]
trussx = "0.2"
```

## Usage

```rust
use trussx::{force, point, Truss};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create a new truss structure
    let mut truss = Truss::new();

    // Define joints
    let a = truss.add_joint(point(0.0, 0.0, 0.0));
    let b = truss.add_joint(point(1.0, 0.0, 0.0));

    // Apply supports and loads
    truss.set_support(a, [true, true, true])?;
    truss.set_support(b, [false, true, true])?;
    truss.set_load(b, force(-1000.0, 0.0, 0.0))?;

    // Define member between joints
    let ab = truss.add_member(a, b);

    // Member properties must be strictly positive to represent a physical bar.
    truss.set_member_properties(ab, 0.01, 200.0e9)?;

    // Run the analysis and unwrap the result
    truss.evaluate()?;

    // Retrieve and print the displacement at joint B
    let displacement = truss.joint_displacement(b).unwrap();
    println!("ux = {:.3e} m", displacement.x);
    Ok(())
}
```

Both the cross-sectional area and elastic modulus must be strictly positive. The library
rejects zero or negative inputs with a descriptive
[`TrussEditError`](https://docs.rs/trussx/latest/trussx/enum.TrussEditError.html) so incorrect
data is surfaced before attempting an analysis.

## Testing

The project includes unit tests that validate the analysis results for a simple bar in
tension and ensure meaningful error reporting when required data is missing. Run the
full suite with:

```bash
cargo test
```

### Member safety factors

Assign a yield strength to each member with `set_member_yield_strength` to enable factor of
safety calculations. During `Truss::evaluate` the library compares the absolute yield
strength to the absolute axial stress for each analysed member and stores the ratio. You can
read the value back with `member_factor_of_safety`.

`member_factor_of_safety` returns `None` when:

- No yield strength has been assigned to the member.
- The structure has not been analysed since the last modification.
- The computed axial stress is effectively zero (no meaningful demand).
- The resulting ratio is not a finite floating-point number.

The repository includes an executable example that demonstrates the workflow
end-to-end:

```bash
cargo run --example factor_of_safety
```

See [`examples/factor_of_safety.rs`](examples/factor_of_safety.rs) for the full
source. The integration tests under [`tests/`](tests/) mirror the same
cantilever scenario to provide executable documentation for the API without
requiring a standalone CLI.