NDTable

A C library to inter- and extrapolate values on regular N-dimensional grids.

Highlights

• pure C — no dependencies
• multi-dimensional — up to 32 dimensions
• interpolation — hold, nearest, linear, Akima, Fritsch–Butland, Steffen
• extrapolation — hold, linear, none
• derivatives — partial derivatives w.r.t all dimensions

Quick start

#include "NDTable.h"

int main(void) {
    int ndims = 1;
    int dims[] = { 3 };
    double data[] = { 0.0, 1.0, 4.0 };
    const double *scales[] = { (const double[]){ 0.0, 1.0, 2.0 } };

    NDTable_h table = NDTable_create_table(ndims, dims, data, scales);
    if (!table) {
        return 1;
    }

    double params[] = { 1.5 };
    double value = 0.0;
    double derivative = 0.0;

    if (NDTable_evaluate(table, params, 0, NDTABLE_INTERP_LINEAR, NDTABLE_EXTRAP_HOLD, &value, &derivative) == 0) {
        /* value ≈ 2.5 at x = 1.5 with linear interpolation */
    }

    NDTable_free_table(table);
    return 0;
}

License

NDTable is released under the BSD-2-Clause license.