Ddotzer

[btracey]

Fixes 137.

[kortschak]

Not LGTM

My counter proposal is to add the following two test cases to testblas.DoubleOneVectorCases and the subsequent three case to testbals.DoubleTwoVectorCases for the reasons outlined in https://github.com/gonum/blas/issues/138#issuecomment-134771415. This fixes our behaviour as is for cgo, but requires a fix for native to push the n == 0 checks down. It has the additional advantage that it regularises the behaviour.

    {
        Name:   "EmptyStationary",
        X:      []float64{},
        Incx:   0,
        N:      0,
        Panic:  true,
        Dasum:  0,
        Dnrm2:  0,
        Idamax: -1,
        DscalCases: []DScalCase{
            {
                Alpha: -2,
                Ans:   []float64{},
            },
            {
                Alpha: 0,
                Ans:   []float64{},
            },
        },
    },
    {
        Name:   "EmptyReverse",
        X:      []float64{},
        Incx:   -1,
        N:      0,
        Panic:  false,
        Dasum:  0,
        Dnrm2:  0,
        Idamax: -1,
        DscalCases: []DScalCase{
            {
                Alpha: -2,
                Ans:   []float64{},
            },
            {
                Alpha: 0,
                Ans:   []float64{},
            },
        },
    },

    {
        Name:  "Empty",
        X:     []float64{},
        Y:     []float64{},
        Incx:  1,
        Incy:  1,
        N:     0,
        Panic: false,
        DaxpyCases: []DaxpyCase{
            {
                Alpha: 2,
                Ans:   []float64{},
            },
        },
        DrotCases: []DrotCase{
            {
                C:    math.Cos(25 * math.Pi / 180),
                S:    math.Sin(25 * math.Pi / 180),
                XAns: []float64{},
                YAns: []float64{},
            },
        },
        DrotmCases: []DrotmCase{
            {
                P: blas.DrotmParams{
                    Flag: blas.Rescaling,
                    H:    [4]float64{0.9, 0.1, -0.1, 0.5},
                },
                XAns: []float64{},
                YAns: []float64{},
            },
        },
    },
    {
        Name:  "EmptyStationary",
        X:     []float64{},
        Y:     []float64{},
        Incx:  0,
        Incy:  0,
        N:     0,
        Panic: true,
        DaxpyCases: []DaxpyCase{
            {
                Alpha: 2,
                Ans:   []float64{},
            },
        },
        DrotCases: []DrotCase{
            {
                C:    math.Cos(25 * math.Pi / 180),
                S:    math.Sin(25 * math.Pi / 180),
                XAns: []float64{},
                YAns: []float64{},
            },
        },
        DrotmCases: []DrotmCase{
            {
                P: blas.DrotmParams{
                    Flag: blas.Rescaling,
                    H:    [4]float64{0.9, 0.1, -0.1, 0.5},
                },
                XAns: []float64{},
                YAns: []float64{},
            },
        },
    },
    {
        Name:  "EmptyReverse",
        X:     []float64{},
        Y:     []float64{},
        Incx:  -1,
        Incy:  -1,
        N:     0,
        Panic: false,
        DaxpyCases: []DaxpyCase{
            {
                Alpha: 2,
                Ans:   []float64{},
            },
        },
        DrotCases: []DrotCase{
            {
                C:    math.Cos(25 * math.Pi / 180),
                S:    math.Sin(25 * math.Pi / 180),
                XAns: []float64{},
                YAns: []float64{},
            },
        },
        DrotmCases: []DrotmCase{
            {
                P: blas.DrotmParams{
                    Flag: blas.Rescaling,
                    H:    [4]float64{0.9, 0.1, -0.1, 0.5},
                },
                XAns: []float64{},
                YAns: []float64{},
            },
        },
    },