how to plot 2 curve with together

Hi. i want to plot below the eqs. in matlab. i want to plot f and f1 with together in one graph and then g and g1 with together in another graph. thank you

m=0:0.01:50;

f=  ((7*m - 7*(m.^2 - (226*m)/7 + 15009/49).^(1/2) + 127)/(7*(3*m + 1))).^(1/2);
f1=  (2.^(1/2)*((3*m + 1)*(m + 1)).^(1/2))/(3*m + 1);


g=((7*m + 7*(m.^2 - (226*m)/7 + 15009/49).^(1/2) + 127)/(7*(3*m + 1))).^(1/2);
g1=-(2^(1/2)*((3*m + 1)*(m + 1)).^(1/2))/(3*m + 1);

[Adam Danz]

You're asking about plotting but the code breaks with an error. So are you asking about that error or about plotting? Whenever you have a question about an error, share the entire error message.

[saman ahmadi]

I want to draw these equations as I said in the previous message. But I can not please help me. Thankful

[Adam Danz]

Why can't you?

Because of an error message?

Because you don't know what functions to use?

We can't help you if we don't understand what the problem is.

Answer 1

[Star Strider]

First, use element-wise multiplication and division:

m=0:0.01:50;

f=  ((7*m - 7*(m.^2 - (226*m)/7 + 15009/49).^(1/2) + 127)./(7*(3*m + 1))).^(1/2);
f1=  (2.^(1/2)*((3*m + 1).*(m + 1)).^(1/2))./(3*m + 1);


g=((7*m + 7*(m.^2 - (226*m)/7 + 15009/49).^(1/2) + 127)./(7*(3*m + 1))).^(1/2);
g1=-(2^(1/2)*((3*m + 1).*(m + 1)).^(1/2))./(3*m + 1);

Then to plot them:

figure
subplot(2,1,1)
plot(m, [f; f1])
legend('f','f1')
grid
subplot(2,1,2)
plot(m, [g; g1])
legend('g','g1')
grid

If you want them in separate figures:

figure
plot(m, [f; f1])
legend('f','f1')
grid

figure
plot(m, [g; g1])
legend('g','g1')
grid

.

[saman ahmadi]

thank you very much

Answer 2

[Adam Danz]

The code results in the error,

Error using  * 
Incorrect dimensions for matrix multiplication. Check that the number of columns in the 
first matrix matches the number of rows in the second matrix. To perform elementwise 
multiplication, use '.*'.

However there are several other errors to address.

First error

The error is happening here in f1

(3*m + 1)*(m + 1)

because you're multiplying a [1x5001] vector by [1x5001] which disobeys matrix multiplication rules.

If you want to multiply those values piece-wise, you'll need to use ".*"

(3*m + 1).*(m + 1)
%        ^

If you want to use matrix multiplication,

(3*m + 1).*(m + 1).'  
%                 ^^

Second error

The same error is in g1. Now you know how to fix that.

Errors 3-5

Judging by you description, it seems that you expect the results to be vectors. The two corrections above will produce scalar values because the division marked below is matrix-division rather than element-wise division. Use "./" instead.

f=  ((7*m - 7*(m.^2 - (226*m)/7 + 15009/49).^(1/2) + 127)./(7*(3*m + 1))).^(1/2);
%                                                        ^

The same is true for f1, g, and g1. Now you know how to fix that.

[saman ahmadi]

thank you very much

Answer 3

[Rik]

doc hold
doc subplot

Or even the documentation of plot itself: direct link.

[saman ahmadi]

thank you