## Inserting and equation and plotting it

### abdo (view profile)

on 25 Nov 2012

i'm trying to insert an equation and plot it, but i couldn't because i keep getting errors like : matrix dimensions must agree, or inner matrix dimensions must agree.

http://www4.0zz0.com/2012/11/25/10/272913238.png

this is the equation. M has a value of 1 to 5 with an increment of 0.5. Q has a value of 0 to 1 with an increment of 0.1.

the plot is something like this.

http://www4.0zz0.com/2012/11/25/10/700692428.png

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### moulay (view profile)

on 25 Nov 2012

Hi!

that is true. length(M)=9 and length (Q)=11. you should take the same length of both vectors. for example Q=0:0.1:0.8!

abdo

### abdo (view profile)

on 25 Nov 2012

thanx for your reply ok i fixed that issue,i tried to split the equation into parts so it would be easier for me to insert it. lets say (d) represents a part d=q/2*m-arccossqrt(1-(q/m)^2); and it gets me this error 1. error using * the inner matrix dimensions must agree thanx in advance

### bym (view profile)

on 25 Nov 2012

use the dot notation to specify element-by-element multiplication/division/exponentiation as in:

```d= q./(2*m)-acos(sqrt(1-(q./m).^2))
```

abdo

### abdo (view profile)

on 25 Nov 2012

thank you, now i have another error for the next part

e=q./m(1-sqrt(1-(q./m).^2));

Subscript indices must either be real positive integers or logicals.

bym

### bym (view profile)

on 27 Nov 2012

yes, you are missing a multiplication. I think what you want is

```e = (m./q).*(1-sqrt(1-(q./m).^2))
```

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