Calling LAPACK/BLAS from Kotlin Native

README.md

Calling LAPACK/BLAS from Kotlin Native

The original C file is cblas_example1.c

$cinterop -def liblapack.def -o build/c_interop/liblapack
$kotlinc-native lapack.kt -library build/c_interop/liblapack
$./program.kexe 
11.0
14.0
17.0
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lapack.kt

import liblapack.*
import kotlinx.cinterop.*


fun main() {
    val m = 4; /* Size of Column ( the number of rows ) */
    val n = 4; /* Size of Row ( the number of columns ) */
    val lda = 4; /* Leading dimension of 5 * 4 matrix is 5 */
    val incx = 1;
    val incy = 1;
    val alpha = 1.0;
    val beta = 0.0;

    memScoped {
        val a = cValuesOf(
            1.0, 2.0, 3.0, 4.0,
            1.0, 1.0, 1.0, 1.0,
            3.0, 4.0, 5.0, 6.0,
            5.0, 6.0, 7.0, 8.0
        )
        val x = cValuesOf(1.0, 2.0, 1.0, 1.0)
        var y = nativeHeap.allocArray<DoubleVar>(4)

        cblas_dgemv(CblasColMajor, CblasNoTrans,
                    m, n, alpha, a, lda, x, incx, beta, y, incy)

        val yp = y.getPointer(ArenaBase())

        for(i in 0..3) {
            println(yp[i])
        }
    }
}

liblapack.def

headers = lapacke.h \
    openblas/cblas.h
headerFilter = openblas/*

compilerOpts.linux = -I/usr/include -I/usr/include/x86_64-linux-gnu
linkerOpts.linux = -L/usr/lib -L/usr/lib/x86_64-linux-gnu -llapacke -llapack -lopenblas