Either expand to an IfExpr to special-case the non-numbers or use number() to force explicit conversions and obtain NaN as under 1.0.

或者扩展 IfExpr 引入非数字的特殊情况，或者像 1.0 那样使用 number() 强制显式转换得到 NaN。

youdao

Many routines designed to read floats may allow values such as "NaN" (not a number).

许多设计用来读取浮点数的例程可能会允许“NaN”(非数字)这样的值。

youdao

Liu Spring Ji Nan is honored as"spring city"because there are many big and small springs everywhere.

《刘氏泉》 济南被誉为“泉城”，是因为市内各处都有很多大小泉眼。

youdao

The price of a popular Iranian bread, known as nan-e sangak, has risen by about 30% in the past few months, according to Iranians.

WSJ: Iran Buying Wheat, Fearing More Curbs

She was as close to my mum as I'd been to my nan.

BBC: Tia Sharp: Murder 'shattered family's hearts'

Keynote addresses were delivered by Dr Rufno Mauricio, Secretary of Department of Education of FSM, Prof Kataoka, representing Japan Consortium for International Cooperation in Cultural Heritage (JCIC-Heritage), as well as Wasa Lapalap Isipahu, Nahnmwarki of Madolenihmx, Traditional Chief of the region in which Nan Maol is located.

UNESCO: OFFICE IN APIA