WP 34S solve an integral

[BarryMead]

(04-24-2015 12:34 PM)Dieter Wrote:  

Code:

LBL A
STO 00      //Save target integral result desired
DROP        //Lower stack to get Upper/Lower solve guess bounds
SLV 00
RTN
ERR 20      //If solve fails to find a root show this error
LBL 00
 0
∫ 01      // ∫ from x to 0 = –∫ from 0 to x 
RCL+ 00   // 10 – ∫
RTN
LBL 01
x²
RTN

Very cleaver optimization. I knew that my original program was clumsy, and non-optimal. I did that on purpose to make it as clear and obvious as possible how to turn the original idea into a program. Using reversed integral bounds (to make the integral negative), and adding a positive target value is equivalent to subtracting a target, and the ability of solve to converge regardless of the sign of the error also can make the program more compact. Congrats on how small you made the program.