es from 0.0 at
            <math overflow="scroll">

                <mrow>
                    <mi mathvariant="italic">z</mi>
                    <mo>=</mo>
                    <mrow>
                        <mo>-</mo>
                        <mi mathvariant="italic">radius</mi>
                    </mrow>
                </mrow>
            </math>
            to 1.0 at
            <math overflow="scroll">

                <mrow>
                    <mi mathvariant="italic">z</mi>
                    <mo