( Free42 ) Decibel Addition and Subtraction - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Software Libraries (/forum-10.html) +--- Forum: General Software Library (/forum-13.html) +--- Thread: ( Free42 ) Decibel Addition and Subtraction (/thread-15110.html) ( Free42 ) Decibel Addition and Subtraction - Gamo - 06-01-2020 12:50 PM This program is adapted from HP-41C Heating, Ventilation and Air Conditioning Page 65 Assign [dB-] and [dB+] to Soft Menu Example 1: A noise level of 72 dB is measured in a room. The air conditioning is turned on and the noise level increases to 74 dB What is the noise level of the air conditioning system. [FIX] 02 74 [ENTER] 72 [dB-] display 69.67 dB Example 2: A compressor is known to have a sound pressure level of 90 dB. The background noise is 85 dB. What is the total? 90 [ENTER] 85 [dB+] display 91.19 dB ----------------------------------------------------------------------- Program: Code: ``` 00 { 51-Byte Prgm } 01 LBL "dB+" 02 XEQ 00 03 + 04 GTO 01 ---------------------- Add Decibels. 05 LBL "dB-" 06 XEQ 00 07 - 08 ABS ---------------------- Subtract Decibels. 09 LBL 01 10 LOG 11 10 12 x 13 CLA 14 ARCL  ST X 15 ⊢"dB" 16 AVIEW 17 RTN --------------------- Display Result. 18 LBL 00 19 10 20 STO÷ ST Z 21 ÷ 22 X<>Y 23 10↑X 24 X<>Y 25 10↑X --------------------- Convert for Add or Subtract.``` Remark: When Subtracting dB(1) < dB(2), the program will exchange values. Gamo 6/1/2020