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Chapters: 1: Introduction 2: Simple example 3: Invocation 4: Finer Control 5: X-Y Plots 6: Contour Plots 7: Image Plots 8: Examples 9: Gri Commands 10: Programming 11: Environment 12: Emacs Mode 13: History 14: Installation 15: Gri Bugs 16: Test Suite 17: Gri in Press 18: Acknowledgments 19: License Indices: Concepts Commands Variables |
9.3.8: `
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`differentiate {x|y wrt index|y|x} | {grid wrt x|y}'
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Differentiate column data or grid data. Only the `x' and `y'
columns may be differentiated. They may be differentiated either with
respect to (``wrt'') the index (forming a first difference) or with
respect to the other column. The derivative is done with the
backwards-difference algorithm. Grid data may differentiated with
respect to `x' direction or `y' direction. Grid
differentiation is done with a centred difference, with endpoints being
assigned the derivative of the neighboring interior point (so that the
second derivative is zero at the edges of the grid).
