struct S {
    float2 v;
};

void initialize(out S[2] z) {
    z[0].v = float2(0, 1);
    z[1].v = float2(2, 1);
}

half4 main(float2 coords) {
    float2 x[2];
    x[0] = float2( 0, 0);
    x[1] = float2( 1, 0);
    float2 y[2];
    y[0] = float2( 0, 1);
    y[1] = float2(-1, 2);
    S z[2];
    initialize(z);

    return half4(x[0][0] * x[0][1] + z[0].v[0],   // R=0
                 x[1][0] - x[1][1] * z[0].v[1],   // G=1
                 y[0][0] / y[0][1] / z[1].v[0],   // B=0
                 y[1][0] + y[1][1] * z[1].v[1]);  // A=1
}