Cascade Historian: Version 4.1
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hist_scale_buffer

hist_scale_buffer -- performs offset and scaling operations.

Syntax

hist_scale_buffer (buffer, xscale, xoffset, yscale, yoffset)

Parameters

buffer

A binary buffer of X-Y pairs of doubles, created by a call to hist_buffer_id_read.

xscale, xoffset

The X value of the data pairs is transformed as follows:

    x' = x * xscale + xoffset
yscale, yoffset

The Y value of the data pairs is transformed as follows:

    y' = y * yscale + yoffset

Returns

t (true) if the transformation was performed with no errors, otherwise nil.

Description

This function performs an offset and scaling transformation on a binary buffer of X-Y data pairs. The buffer is modified in place (i.e., a new buffer is not created, and the old values cannot be recovered). This function can be used to adjust data for graphing.

This function corresponds to the Cogent API function HI_ScaleBuffer.

Example

    // To shift the Y data by 100 units:
    hist_scale_buffer (data, 1, 0, 1, 100);

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