How to count matrix rows in another metric system

[layer]

I use QwtMatrixRasterData
screen_1.png
Y-axis: we have 30 rows here in matrix data.

but I have to count in "mm"
for example three rows of matrix it's a 1 mm, thus I need to change scale without changing the matrix, how can I do it?

thank you!

[Uwe]

[QUOTE=layer;244252Y-axis: we have 30 rows here in matrix data - for example three rows of matrix it's a 1 mm, ..[/QUOTE]
1.0 mm : 3.0 * 30 = 10 mm

data->setInterval( Qt::YAxis, 10.0 );

data->setInterval( Qt::YAxis, 10.0 );

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Uwe

[layer]

1.0 mm : 3.0 * 30 = 10 mm

data->setInterval( Qt::YAxis, 10.0 );

data->setInterval( Qt::YAxis, 10.0 );

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Uwe

it seems like setInterval(Qt::Axis, double&)
but it needs

virtual void QwtMatrixRasterData::setInterval(Qt::Axis, const QwtInterval&)

virtual void QwtMatrixRasterData::setInterval(Qt::Axis, const QwtInterval&)

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or I didn't catch something?

so then I wrote this snippet:

setInterval(Qt::YAxis, QwtInterval(0, 10, QwtInterval::ExcludeMaximum));

setInterval(Qt::YAxis, QwtInterval(0, 10, QwtInterval::ExcludeMaximum));

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and it doesn't work, what I did wrong?