# Using Manipulate on a piecewise function made of specific parameters ?

Posted 1 year ago
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 Hi, I'm trying to put on Mathematica a graph of my model that is displaying a piecewise function with specific parameters. The aims being to see how the parameters will affect the graph I wanted to do it on Mathematica with manipulate. I join the Mathematica file to my question hopping one can tell me why I cannot see anything else than a blank sheet. I tried to do it in two stages as my tries in once were giving something worst. Thanks in advance for any advice that I might use!This is the piecewise function I need to graph. fb[Fc_] := Piecewise[{{a^2 (1 + \[Beta] (1 - p))/ 2 (1/(2 (b + cB + \[Tau]*\[Theta]B)) - 1/( 2 (b + cA + \[Tau]*\[Theta]A))), 0 <= Fc <= a^2/2 (1/(2 (b + cC + \[Tau]*\[Theta]C)) - 1/( 2 (b + cB + \[Tau]*\[Theta]B)))}, {a^2 ((1 + \[Beta])/( 2 (b + cB + \[Tau]*\[Theta]B)) - (1 + \[Beta] (1 - p))/( 2 (b + cA + \[Tau]*\[Theta]A)) - (\[Beta]* p)/( 2 (b + cC + \[Tau]*\[Theta]C))) + \[Beta] *p*Fc, a^2/2 (1/(2 (b + cC + \[Tau]*\[Theta]C)) - 1/( 2 (b + cB + \[Tau]*\[Theta]B))) < Fc <= a^2/2 (1/(2 (b + cC + \[Tau]*\[Theta]C)) - 1/( 2 (b + cA + \[Tau]*\[Theta]A)))}}] And this is how I try to plot it: Manipulate[ Plot[fb[Fc_], {Fc, 0, a^2/2 (1/(2 (b + cC + \[Tau]*\[Theta]C)) - 1/( 2 (b + cA + \[Tau]*\[Theta]A)))}], {a, 1, 5}, {\[Theta]A, 0, 1}, {\[Theta]B, 0, 1}, {\[Theta]C, 0, 1}, {\[Tau], 0, 3}, {cA, 2, 3}, {cB, 1, 2}, {cC, 0, 1}, {b, 0, 1}, {p, 0, 1}, {\[Beta], 0, 1}] Attachments: Answer
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Posted 1 year ago
 Hi Xavier,There are at least two issues Plot[fb[Fc_], ...] should be Plot[fb[Fc], ...] After fixing that Power::infy: Infinite expression 1/0 encountered. The range for Fc includes this expression 1/(2 (b + cC + τ*θC)) The range for b, cC, τ and θC in the Manipulate all start at 0 causing the 1/0 error. Answer
Posted 1 year ago
 Thank you for your comment! Indeed I forgot to put at least 0.1 however I still do not see anything when looking at the graph... :/ Answer
Posted 1 year ago
 After applying Rohits fixes and tweaking a bit, this will show a graph: Manipulate[ Plot[ fb[Fc], {Fc, 0, a^2/2 (1/(2 (b + cC + \[Tau]*\[Theta]C)) - 1/(2 (b + cA + \[Tau]*\[Theta]A)))}, Exclusions -> None, PlotRange -> Full, AxesOrigin -> {0,0} ], {{a,2}, 1, 5}, {\[Theta]A, 0, 1}, {\[Theta]B, 0, 1}, {\[Theta]C, 0.1, 1}, {\[Tau], 0.1, 3}, {cA, 2, 3},{cB, 1, 2}, {cC, 0.1, 1}, {b, 0.1, 1}, {p, 0, 1}, {\[Beta], 0, 1}, SaveDefinitions -> True ] Answer
Posted 1 year ago
 Thanks a lot for your help this problem is now fixed! Answer