pointed bracket or singular function

11252014, 07:09 AM
Post: #1




pointed bracket or singular function
in creating a function for that deflection of a beam requires, I am told, the use of pointed brackets or a singular function. If the term within the brackets < > evaluates less than zero, the term becomes zero, something like this
y = 5*x^3 + 180*<x1>^2  10/12 * <x2>^4 + 10/12*<x4>^4  10*<x5>^3  535*x is there anyway to input this formula into the HP Prime where the terms in < > will drop out if they evaluation less than zero???? 

11252014, 01:24 PM
Post: #2




RE: pointed bracket or singular function
(11252014 07:09 AM)resolved Wrote: in creating a function for that deflection of a beam requires, I am told, the use of pointed brackets or a singular function. If the term within the brackets < > evaluates less than zero, the term becomes zero, something like this Would a piecewise function fit your needs? \[ f(x) = 5x^3  535x + \begin{cases} 180(x1)^2, & x \ge 1\\ 0, & x<1 \end{cases} + \begin{cases} \frac{10}{12}(x2)^4, & x \ge 2\\ 0, & x < 2 \end{cases} + \begin{cases} +\frac{10}{12}(x4)^4, & x \ge 4\\ 0, & x < 4 \end{cases} + \begin{cases} 10(x5)^3, & x\ge 5\\ 0, & x<5 \end{cases} \] The piecewise functions can be created via the template key Graph 3D  QPI  SolveSys 

11252014, 05:30 PM
Post: #3




RE: pointed bracket or singular function
(11252014 07:09 AM)resolved Wrote: in creating a function for that deflection of a beam requires, I am told, the use of pointed brackets or a singular function. If the term within the brackets < > evaluates less than zero, the term becomes zero, something like this You can use the MAX (maximum) function (Math menu, Arithmetic) and type (for example) MAX(0,x1). Nigel (UK) 

11262014, 10:32 AM
Post: #4




RE: pointed bracket or singular function
thanks Han and Nigel, both worked, much better than my solution of creating five different equations in Solver to evaluate


12012014, 04:11 PM
(This post was last modified: 12012014 04:29 PM by Han.)
Post: #5




RE: pointed bracket or singular function
(11262014 10:32 AM)resolved Wrote: thanks Han and Nigel, both worked, much better than my solution of creating five different equations in Solver to evaluate Take care as they are not equivalent. For example, MAX((x2)^2,0) is always the same as just (x2)^2, whereas MAX((x2)^3,0) is the same as \[ f(x) = \begin{cases} (x2)^3, & x\ge 3\\ 0, & x<3 \end{cases} \] I'm not quite sure which it is you want, though your original post says that that if the expression inside the < > is negative, then entire term is 0. That is not the same thing as using the MAX() function. Thus <x2>^2 should be 0 for x<2. However, MAX((x2)^2,0) is positive if x<2. Edit: I may have misinterpreted the posts. If you indeed meant what you originally wrote, then MAX(x2,0)^2 (note the square on the outside) would work just fine. Graph 3D  QPI  SolveSys 

12042014, 10:45 AM
Post: #6




RE: pointed bracket or singular function
thanks Han for your thoughts, yes I wanted the pointed bracets evaluated before it is squared.


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