Latex Troubleshoot: Sizing \mid Signs

[Math Amateur]

In a recent post on the Analysis Forum I tried the following Latex code in order to size the \mid signs ...\left\mid \frac{f_j ( a + h ) - f_j (a)}{ h } - x_j \right\mid^2 \le \| \frac{ f( a + h ) - f(a) }{ h } - ( x_1, \ ... \ ... \ , x_m ) \|^2
The code failed ... but why?Can someone please help ... Peter

 

[MarkFL]

[m]\mid[/m] is constructed as a relation symbol and is not set up to take a size-modifying prefix. Try using:

$$\left\vert \frac{f_j ( a + h ) - f_j (a)}{ h } - x_j \right\vert^2 \le \| \frac{ f( a + h ) - f(a) }{ h } - ( x_1, \ ... \ ... \ , x_m ) \|^2 $$

Is that what you were after?

 

[Math Amateur]

[m]\mid[/m] is constructed as a relation symbol and is not set up to take a size-modifying prefix. Try using:

$$\left\vert \frac{f_j ( a + h ) - f_j (a)}{ h } - x_j \right\vert^2 \le \| \frac{ f( a + h ) - f(a) }{ h } - ( x_1, \ ... \ ... \ , x_m ) \|^2 $$

Is that what you were after?

Yes, Mark ... exactly the help I needed!

Thanks ...

Peter