simple problem about plotting

hello guys;

I am trying to plot a mathematics graph..

The graph is

 y=(x+895.185)*(42.036*sqrt(x+657.509)-1656.4)-42.036*sqrt(x+657.509)*(x+1790.37)+2234.91*x+2.484*10.^6;

I made a code for this like below.

x=(0:0.1:1000);

y=(x+895.185)*(42.036*sqrt(x+657.509)-1656.4)-42.036*sqrt(x+657.509)*(x+1790.37)+2234.91*x+2.484*10.^6;

but I got the error massage...

how can I solve it?

thank you!

Answer 1

[Image Analyst]

When you multiply a vector by another vector element by element, you need to use .* instead of * otherwise it tries to do a matrix multiplication. Fixed code:

y=(x+895.185).*(42.036*sqrt(x+657.509)-1656.4)-42.036*sqrt(x+657.509).*(x+1790.37)+2234.91*x+2.484*10.^6;

[Geonhee LEE]

thank you!!

So when I use (), is it considered as vector in matlab?

[Image Analyst]

No. When you did

x=(0:0.1:1000);

you made a vector. The parentheses were optional and unneeded. You could just have well have done

x = 0 : 0.1 : 1000;

and that would have been a vector too. And of course "sqrt(x+657.509)" is also a vector, and "(x+895.185)" is also a vector, and so is "(x+1790.37)" and "2234.91*x". You do not need a dot if you're multiplying a scalar (single number) times a vector, just when you want to multiply two vectors element by element, and of course they need to be the same length.

[Geonhee LEE]

I got it!!

thank you for your kind answering!!