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cl:functions:math-one-plus [2019/09/14 05:00]
cl:functions:math-one-plus [2019/09/22 06:00] (current)
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 +====== Function 1+, 1- ======
 +
 +====Syntax====
 +  * **1+** //number// → //​successor// ​
 +  * **1-** //number// → //​predecessor//​
 +
 +====Arguments and Values====
 +  * //number// - a //​[[CL:​Glossary:​number]]//​.
 +  * //​successor//,​ //​predecessor//​ - a //​[[CL:​Glossary:​number]]//​.
 +
 +====Description====
 +**1+** returns a //​[[CL:​Glossary:​number]]//​ that is one more than its argument //number//. **1-** returns a //​[[CL:​Glossary:​number]]//​ that is one less than its argument //number//.
 +
 +====Examples====
 +<​blockquote> ​
 +(1+ 99) <​r>​100 </r>
 +(1- 100) <r>99 </r>
 +(1+ ([[CL:​Functions:​complex]] 0.0)) <​r>#​C(1.0 0.0) </r>
 +(1- 5/3) <​r>​2/​3 </r>
 +</​blockquote>​
 +
 +====Affected By====
 +None.
 +
 +====Exceptional Situations====
 +Might signal **[[CL:​Types:​type-error]]** if its //​[[CL:​Glossary:​argument]]//​ is not a //​[[CL:​Glossary:​number]]//​. Might signal **[[CL:​Types:​arithmetic-error]]**.
 +
 +====See Also====
 +  * **[[CL:​Macros:​incf|Macro INCF]]**
 +  * **[[CL:​Macros:​decf|Macro DECF]]**
 +
 +====Notes====
 +<​blockquote> ​
 +(1+ //number//) ≡ ([[CL:​Functions:​math-add|+]] //number// 1) 
 +(1- //number//) ≡ ([[CL:​Functions:​math-subtract|-]] //number// 1) 
 +</​blockquote>​
 +
 +Implementors are encouraged to make the performance of both the previous expressions be the same.
 +