未将输出参数分配给子函数的程序时如何解决

Question

铁的饮用水标准为0.3mg / L。同样，镁的标准为0.05mg / L。创建一个程序，该程序将吸收铁和镁的测量值，并显示水是否可以安全饮用。

我已经启动了先测试Iron的程序，然后将创建针对Magnesium的另一个程序测试。我的问题是我必须使用子功能来解决程序，并且得到正确的答案，但是命令窗口中出现错误。我知道它必须包含test=testWater(IronSafe)，因为我尚未声明输出语句，而且不确定如何将其实现到代码中。

function [IronStand] = ProblemWATER(IronSafe)
%Create a function that states whether H20 for iron is safe to drink
% 1 inputs: IronSafe
% 1 output:IronStand 
IronSafe = input('What is the density level of your iron \n');
IronStand = testWater(IronSafe);
end
function test= testWater(IronSafe)
%Subfunction meant to determine if IronStand drinkable
IronStand = 0.3;
if IronSafe == IronStand
    disp('Safe to drink'); 
else 
    disp('Not safe');
end
end

我的命令窗口显示：

Answer 1

问题出在您的第二个功能function test= testWater(IronSafe)中。您正在返回值test，但从未将其分配给任何值。您可以通过删除它来解决它：

function [] = ProblemWATER(IronSafe)
%Create a function that states whether H20 for iron is safe to drink
% 1 inputs: IronSafe
% 1 output:IronStand 
IronSafe = input('What is the density level of your iron \n');
testWater(IronSafe);
end

function [] = testWater(IronSafe)
%Subfunction meant to determine if IronStand drinkable
IronStand = 0.3;
if IronSafe == IronStand
    disp('Safe to drink'); 
else 
    disp('Not safe');
end
end

如果您想返回IronStand的值，则需要更改返回值：

function [IronStand] = ProblemWATER(IronSafe)
%Create a function that states whether H20 for iron is safe to drink
% 1 inputs: IronSafe
% 1 output:IronStand 
IronSafe = input('What is the density level of your iron \n');
IronStand = testWater(IronSafe);
end

function [IronStand] = testWater(IronSafe)
%Subfunction meant to determine if IronStand drinkable
IronStand = 0.3;
if IronSafe == IronStand
    disp('Safe to drink'); 
else 
    disp('Not safe');
end
end