tan100 defined inconsistently

[maikriechert]

In §44 the text says:

The function pair denoted “tan100(1 deg)” is defined as fPD(α) = tan(α) * 100 to convert from a plane angle α to a prism diopter value (or a slope percent value) and fPD-1(x) = arctan(x / 100) to convert from prism diopter (or slope percent) value x back to a plane angle.

Whereas the table below says: 100tan(1 rad)

Looking at the XML file, you find the following:

   <unit Code="[p'diop]" CODE="[P'DIOP]" isMetric="no" isSpecial="yes" class="clinical">
      <name>prism diopter</name>
      <printSymbol>PD</printSymbol>
      <property>refraction of a prism</property>
      <value Unit="100tan(1 rad)" UNIT="100TAN(1 RAD)">
         <function name="tanTimes100" value="1" Unit="deg"/>
      </value>
   </unit>
   <unit Code="%[slope]" CODE="%[SLOPE]" isMetric="no" isSpecial="yes" class="clinical">
      <name>percent of slope</name>
      <printSymbol>%</printSymbol>
      <property>slope</property>
      <value Unit="100tan(1 rad)" UNIT="100TAN(1 RAD)">
         <function name="100tan" value="1" Unit="deg"/>
      </value>
   </unit>

There are two inconsistencies here:

1. There are two different function names for the same thing within the <function> tags: 100tan and tanTimes100.
2. The <function> tag has "deg" as unit, whereas the <value> tag has "100tan(1 rad)".

[Gunther Schadow]

Yes, indeed, the text was off. The table was right. Changed the text from

The function pair denoted “tan100(1 deg)”

to

The function pair denoted “100tan(1 rad)”

The function/@name does not make it into the specification text. It is a name which conforms to naming rules in a typical programming language like Java, that is why it is different. Obviously it was not right with the function/@Unit="deg" in there, so I changed it to:

  <function name="tanTimes100" value="1" Unit="rad"/>