Undefined function 'piecewise' for input arguments of type 'double'. or 'Conversion to logical from sym is not possible.' errors

1 次查看（过去 30 天）
Phuquy Bui
Phuquy Bui 2020-2-13
回答： Ajay Pattassery 2020-2-18
function deflectionV=Deflection_ptbui3(deflPos)
syms deflPos
deflectionV=piecewise((0<deflPos)&&(deflPos<=120),800*(deflPos)^3-13.68*10^6*(deflPos)-2.5*(deflPos)^4,(120<deflPos)&&(deflPos<=240),800*(deflPos)^3-13.68*10^6*(deflPos)-2.5*(deflPos)^4+(2.5*(deflPos-120)^4),(240<deflPos)&&(deflPos<=360),800*(deflPos)^3-13.68*10^6*(deflPos)-2.5*(deflPos)^4+(2.5*(deflPos-120)^4)+(600*(deflPos-240)^3));
deflectionV=(1/3.19E9)*deflectionV;
end
This is my code for the function for my piecewise, but whenever I call for it in my actual script, I get a 'Conversion to logical from sym is not possible.' error.
I've been trying to do this problem where i put the user input into a piecewise function.
Before when I didn't have the syms, it would also just give me 'Undefined function 'piecewise' for input arguments of type 'double'. So i'm not entirely sure whats going on and my teacher nor TA's know very much about the function. And if you think it isn't gonna work, please let me know so I can get the closure to delete this mess of a function. :)

请先登录，再回答此问题。

回答（1 个）

Ajay Pattassery
Ajay Pattassery 2020-2-18
The logical operator && is a short-circuit operator which means the second operand is only evaluated when the result is not fully determined by the first operand. Refer here for more information.
In your case logical and (&) need to be used.
deflectionV=piecewise((0<deflPos)&(deflPos<=120),800*(deflPos)^3-13.68*10^6*(deflPos)-2.5*(deflPos)^4,(120<deflPos)&(deflPos<=240),800*(deflPos)^3-13.68*10^6*(deflPos)-2.5*(deflPos)^4+(2.5*(deflPos-120)^4),(240<deflPos)&(deflPos<=360),800*(deflPos)^3-13.68*10^6*(deflPos)-2.5*(deflPos)^4+(2.5*(deflPos-120)^4)+(600*(deflPos-240)^3));

类别

在 Help Center 和 File Exchange 中查找有关 Assumptions 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by