Help about function with if statement
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I have problem with creating function. I don´t know how to use command function properly. Can you guys tell me where I was wrong it will be very helpful
function [y]=task1(x)
if x>=8
y = 14*(5*x)^(1/2)+9;
end
if (-1<=x<8)
y=9*x +9;
end
if (x<-1) y=9;
end
1 Comment
Jan
on 18 Dec 2016
Why do you assume, that something is wrong? Which problem do you observe? Do you get an error message?
Answers (2)
laaj
on 18 Dec 2016
function output=task1(x)
if x>=8
y = 14*(5*x)^(1/2)+9;
end
if (-1<=x<8)
y=9*x +9;
end
if (x<-1)
y=9;
end
output=[y];
I don't know much but I just hope it will solve the problem.
0 Comments
Jan
on 18 Dec 2016
Edited: Jan
on 18 Dec 2016
"if (-1<=x<8)" does most likely not do, what you expect. Matlab processes this expression from left to right: "-1<=x" replies TRUE or FALSE depending on the value of x. In the next step you have "TRUE<8" or "FALSE<8". While TRUE is converted to 1, FALSE is a 0, and both values are smaller than 8. You need two comparisons: "-1 <= x" and "x < 8":
function y = task1(x)
if x >= 8
y = 14 * (5 * x)^(1 / 2) + 9;
elseif -1 <= x && x < 8
y = 9 * x + 9;
elseif x < -1
y = 9;
end
Now you can simplify this: If you have excluded x>=8 already, you do not have to check for x<8 anymore:
function y = task1(x)
if x >= 8
y = 14 * sqrt(5 * x) + 9; % SQRT is cheaper than ^0.5
elseif -1 <= x
y = 9 * x + 9;
else
y = 9;
end
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