General ⇒ Incrementing parentequation counter difficulty

[Diff Eq]

I've been going through the documentation for AMS and they mention that:

The counters used by the subequations environment
are parentequation and equation and \addtocounter, \setcounter,
\value, etc., can be applied as usual to those counter names.

How do you increase the parentequation counter? \addtocounter{parentequation}{1}? That doesn't seem to work?

So, I want to go:

Code: Select all

\begin{subequations}
\begin{subequations}
\begin{align}
	\mathbf{ECEP}_b& =0.5887(\sigma_{max}+\sigma_{min})\\
	\intertext{or in normalized form:}
	\mathbf{ECEP}_b& =0.5887\big((1+t)\sigma_{max}\big)\\
	\intertext{The other approximate solutions are:}\addtocounter{parentequation}{1}\setcounter{equation}{0}
	\mathbf{ECEP}_b& =0.8326(\sigma_{max}^2+\sigma_{min}^2)^{1/2}
	\intertext{or in normalized form:}
	\mathbf{ECEP}_b& =0.8326(1+t^2)^{1/2}\sigma_{max}
\end{align}
\end{subequations}\end{subequations}

The result would have an equation layout of:

Eq. 6a
Eq. 6b
Eq. 7a
Eq. 7b

It's currently displaying

Eq. 6a
Eq. 6b
Eq. 6a
Eq. 6b

Thanks again for your help!

[pumpkinegan]

Would you try:

Code: Select all

\begin{subequations}
\begin{align}
   \mathbf{ECEP}_b& =0.5887(\sigma_{max}+\sigma_{min})\\
   \intertext{or in normalized form:}
   \mathbf{ECEP}_b& =0.5887\big((1+t)\sigma_{max}\big)
\end{align}
\end{subequations}
The other approximate solutions are:
\begin{subequations}
\begin{align}
   \mathbf{ECEP}_b& =0.8326(\sigma_{max}^2+\sigma_{min}^2)^{1/2}
   \intertext{or in normalized form:}
   \mathbf{ECEP}_b& =0.8326(1+t^2)^{1/2}\sigma_{max}
\end{align}
\end{subequations}

Further, I would not recommend forcing parenthesis sizing using \big(. Use \left [ instead (although in this case it has no effect):

Code: Select all

\mathbf{ECEP}_b& =0.5887\left[ (1+t) \sigma_{max} \right]