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>comedi_get_softcal_converter</H1
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><H2
>Name</H2
>comedi_get_softcal_converter -- get converter for software-calibrated subdevice</DIV
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>Synopsis</H2
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><PRE
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>#include <comedilib.h></PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int comedi_get_softcal_converter</CODE
>(unsigned subdevice, unsigned channel, unsigned range, enum comedi_conversion_direction direction, const comedi_calibration_t *parsed_calibration, comedi_polynomial_t *converter);</CODE
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> Status
</H2
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> alpha
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><H2
> Description
</H2
><P
>comedi_get_softcal_converter() initializes <CODE
CLASS="PARAMETER"
>converter</CODE
> so it can be
passed to either comedi_to_physical() or comedi_from_physical(). The <CODE
CLASS="PARAMETER"
>converter</CODE
>
parameter can then be used to
convert data from the specified <CODE
CLASS="PARAMETER"
>subdevice</CODE
>,
<CODE
CLASS="PARAMETER"
>channel</CODE
>, and <CODE
CLASS="PARAMETER"
>range</CODE
>. The <CODE
CLASS="PARAMETER"
>direction</CODE
>
parameter specifies whether <CODE
CLASS="PARAMETER"
>converter</CODE
> will be passed to comedi_to_physical()
or comedi_from_physical(). The <CODE
CLASS="PARAMETER"
>parsed_calibration</CODE
> parameter contains the
software calibration values for your device, and may be obtained by calling comedi_parse_calibration_file()
on a calibration file generated by the comedi_soft_calibrate program.</P
><P
>This function is only useful for boards that perform their calibrations in software on the host
computer. A subdevice will advertise the fact that it depends on a software calibration
with the SDF_SOFT_CALIBRATED subdevice flag.</P
><P
>Whether or not the result of this function actually depends on the <CODE
CLASS="PARAMETER"
>channel</CODE
>
parameter is
hardware dependent. For example, a multiplexed analog input will typically use the same
calibration for all input channels. Analog outputs will typically use different calibrations
for each output channel.</P
><P
>Software calibrations are implemented as polynomials (up to third order). Since the inverse
of polynomials of order higher than one can't be represented exactly as another polynomial, you
may not be able to get converters for the "reverse" direction. For example, you may be
able to get a converter for an analog input in the COMEDI_TO_PHYSICAL direction, but not
in the COMEDI_FROM_PHYSICAL direction.
</P
></DIV
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><A
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><H2
> Return value
</H2
><P
>Zero on success or -1 on failure.
</P
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