online_inherently_unstable:    Computation of the inherently UNSTABLE channel [Beta version 1.0 - 160530] Reference INPUT DATA: [ Recommended range ] [ How to use ] Half bottom width B* : [ 0.5 ≤ B* ≤ 10 m ] Depth of lower subsection ho : [ 0.5 ≤ ho ≤ 5 m ] Side slope of lower subsection z : [ 0 ≤ z ≤ 3 ] Relative depth hu' : [ 0.5 ≤ hu' ≤ 3 ] Channel slope So : [ 0.01 ≤ So ≤ 0.1 ] Manning's n : [ 0.01 ≤ n ≤ 0.03 ] Neutrally stable Froude number Fns :       A. 10000 B. 5000 C. 1000 D. 100 E. 50 F. 25 G. 20 H. 10 I. 5 J. 3 No. of output lines NL : [ 5 ≤ NL ≤ 20 ]  [ Leave blank to set default = 10 ] OUTPUT: Warning: Undefined variable $froudein in /var/www/html/ponce/onlineinherentlyunstable.php on line 557 Warning: Trying to access array offset on null in /var/www/html/ponce/onlineinherentlyunstable.php on line 557 Fatal error: Uncaught DivisionByZeroError: Division by zero in /var/www/html/ponce/onlineinherentlyunstable.php:557 Stack trace: #0 {main} thrown in /var/www/html/ponce/onlineinherentlyunstable.php on line 557