plot with equals in matlab

hey, what is the problem with this code -

x=linespace(-10,10,2);
yy=sin(x)+0.2*sin(2x)-0.3*sin(3x);
zz=1/0.1+abs(sin(x)+0.2*sin(2x)-0.3*sin(3x));
hold on
plot(x,yy,'--g')
plot(x,zz,'-r')
hold off
axis equal
grid on
legend('y(x)','g(x)')

i get this note -

Error: File: Untitled4 Line: 3 Column: 20

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax

error. To construct matrices, use brackets instead of parentheses.

Answer 1

[Walter Roberson]

yy=sin(x)+0.2*sin(2x)-0.3*sin(3x);

MATLAB has absolutely no implied multiplication anywhere. Not even in the symbolic toolbox. 2x is not a valid expression in MATLAB.

The only cases in which a number can be directly followed by a letter in MATLAB are:

• in the middle of an identifier (which would have to start with a letter, not a number or underscore)
• in a single-quoted character vector or double-quoted string object
• in a comment
• A number may be directly followed by i or j to indicate multiplication by sqrt(-1), such as 5i meaning 5*sqrt(-1). i and j are case-sensitive for this purpose
• A number may be directly followed by e or E or d or D provided that is followed by an optional + or - that is then followed by an integer; this indicates an exponent. For example 5.2e3
• A 0 at the beginning of a number may be immediately followed by a b that is then followed by a series of 0 and 1 to indicate binary numbers. The sequence of binary numbers may be followed by s or u and then the integer 8, 16, 32, or 64
• A 0 at the beginning of a number may be immediately followed by a x that is then followed by a series of hex digits 0 to 9, A-F or a-f, to indicate hexadecimal numbers. The sequence of hexadecimal numbers may be followed by s or u and then the integer 8, 16, 32, or 64

In all other cases, you need an operator between the number and the letter, such as 2*x intead of 2x.

[Noa Yelin]

ok, I wrote this code like this -

%%task number 1
x=linespace(-10,10,100);
yy=sin(x)+0.2*sin(2*x)-0.3*sin(3*x);
zz=1/0.1+abs(sin(x)+0.2*sin(2*x)-0.3*sin(3*x));
hold on
plot(x,yy,'--g')
plot(x,zz,'-r')
hold off
axis equal
grid on
legend('y(x)','g(x)')

and then, the note was -

Error in Untitled4 (line 2)

x=linespace(-10,10,100);

[Walter Roberson]

There is no MATLAB function named linespace, but there is a linspace ( lin not line )

[Walter Roberson]

Is there a point in calculationg 1/0.1 instead of just writing 10 instead?

Or is zz supposed to be 1 divided by a long expression? Remember to use () as needed.

[Noa Yelin]

Thank you! I did it!