Parse error Simple Function Problem

Hi I am brand new to matlab and am writing a simple program for an assignment. We are given a piecewise function with three parts of the height of a rocket. and are supposed to write a function to calculate the height. I did this but am getting a parse error for the t's inside the if and if elses. Any guidance is much appreciated!

Function[y]=height(t)

if(t<0)
   y=0;
elseif(t<15)
   y=38.1454t+0.13743t^3;
elseif((t<33)&&(t>=15)
   y=1036+103.909(t-15)+6.18425(t-15)^2-0.428(t-15)^3;
elseif(t>33)
   y=2900-62.468(t-33)-16.9274(t-33)^2+0.41796(t-33)^3

end

Answer 1

[Star Strider]

You need to specify the multiplication operators (*). I added element-wise exponentiation. You also need to save your function to its own file as height.m on your MATLAB user path.

This is not as efficient as it could be, however it will get you started:

      function [y]=height(t)
          if (t<0)
              y=0;
          elseif (t<15)
              y=38.1454*t+0.13743*t.^3;
          elseif (t<33) & (t>=15)
              y=1036+103.909*(t-15)+6.18425*(t-15).^2-0.428*(t-15).^3;
          elseif (t>33)
              y=2900-62.468*(t-33)-16.9274*(t-33).^2+0.41796*(t-33).^3;
          end
      end

t = linspace(0, 50, 50);

for k1 = 1:numel(t)
    h(k1) = height(t(k1));
end

figure
plot(t, h)
grid

Experiment to get the result you want.

[Walter Roberson]

One thing to pay attention to here is that Star Strider took care to pass in only a single numeric value instead of passing in a vector of values. Your code is not designed to handle vectors of values. You should consider using logical indexing.

Answer 2

[iorngbough iorpinen]

Hi please someone should help out,iam new in MATLAB iam writing a program on two first order differential equation using shooting method and iam getting 'parse'error at the first bracket after the "equal to sign"

Function [dp]=(r,p) E=50;q1=4;q2=-2;B=1672;rho=0.32×10^-9;l=1; do=[p(2);(-2*E-2*q1*q2*r^-1-2*B*exp(-r/rho)+l*(l+1)*r^-2*p(1)];

[Steven Lord]

What's the name of this function? Where are you supposed to specify the name of the function when you write it, and where did you specify the name of this function?

[Star Strider]

@iorngbough iorpinen —

Please post your Answer as a new Question. It does not relate to this thread.

[iorngbough iorpinen]

Please iam sorry it was a mistake