Crate tenferro_tropical_capi 

C-API (FFI) for tropical semiring tensor operations.

Extends [tenferro_capi] with tropical einsum functions for three semirings: MaxPlus (⊕=max, ⊗=+), MinPlus (⊕=min, ⊗=+), and MaxMul (⊕=max, ⊗=×).

Design

• Reuses [TfeTensorF64] handles from tenferro-capi. Since MaxPlus<f64> is #[repr(transparent)], it has the same memory layout as f64. Tropical functions accept f64 tensor handles, internally wrap data as MaxPlus<f64> (or MinPlus/MaxMul), perform the tropical einsum, and unwrap the result back to f64.
• No new handle type — the algebra is selected by the function name, not the tensor type.
• Naming convention: tfe_tropical_einsum_<algebra>_f64.

Linking

This crate produces a separate shared library from tenferro-capi. C/Julia/Python consumers load both:

// Core tensor operations
tfe_tensor_f64 *t = tfe_tensor_f64_from_data(...);

// Tropical einsum (from tenferro-tropical-capi)
const tfe_tensor_f64 *ops[] = {a, b};
tfe_tensor_f64 *c = tfe_tropical_einsum_maxplus_f64("ij,jk->ik", ops, 2, &status);

Example (C pseudocode)

#include "tenferro.h"
#include "tenferro_tropical.h"

tfe_status_t status;
size_t shape[] = {3, 4};
double data_a[12] = { /* ... */ };
double data_b[12] = { /* ... */ };

tfe_tensor_f64 *a = tfe_tensor_f64_from_data(data_a, 12, shape, 2, &status);
tfe_tensor_f64 *b = tfe_tensor_f64_from_data(data_b, 12, shape, 2, &status);

// MaxPlus tropical einsum: C[i,k] = max_j (A[i,j] + B[j,k])
const tfe_tensor_f64 *ops[] = {a, b};
tfe_tensor_f64 *c = tfe_tropical_einsum_maxplus_f64("ij,jk->ik", ops, 2, &status);
assert(status == TFE_SUCCESS);

tfe_tensor_f64_release(c);
tfe_tensor_f64_release(b);
tfe_tensor_f64_release(a);

Functions

tfe_tropical_einsum_frule_maxmul_f64^⚠

Forward-mode rule (JVP) for MaxMul tropical einsum.

tfe_tropical_einsum_frule_maxplus_f64^⚠

Forward-mode rule (JVP) for MaxPlus tropical einsum.

tfe_tropical_einsum_frule_minplus_f64^⚠

Forward-mode rule (JVP) for MinPlus tropical einsum.

tfe_tropical_einsum_maxmul_f64^⚠

Execute tropical einsum under MaxMul algebra (⊕=max, ⊗=×).

tfe_tropical_einsum_maxplus_f64^⚠

Execute tropical einsum under MaxPlus algebra (⊕=max, ⊗=+).

tfe_tropical_einsum_minplus_f64^⚠

Execute tropical einsum under MinPlus algebra (⊕=min, ⊗=+).

tfe_tropical_einsum_rrule_maxmul_f64^⚠

Reverse-mode rule (VJP) for MaxMul tropical einsum.

tfe_tropical_einsum_rrule_maxplus_f64^⚠

Reverse-mode rule (VJP) for MaxPlus tropical einsum.

tfe_tropical_einsum_rrule_minplus_f64^⚠

Reverse-mode rule (VJP) for MinPlus tropical einsum.