On entry: a valid C format code. This should be of the form
$\%\left[\mathit{flag}\right]ww.pp\left[\mathit{format}\text{}\mathit{indicator}\right]$, where
$\mathit{ww}.pp$ indicates that up to two digits may be used to specify the field width and precision respectively. Only % and
$\mathit{format}\text{}\mathit{indicator}$ must be present.
$\mathit{flag}$ can be one of
$-$,
$+$,
$<\text{space}>$ or # and
$\mathit{format}\text{}\mathit{indicator}$ can be e, E, f, g or G. Thus, possible formats include %f,
$\%-11.4\mathrm{G}$, %.6e.
form is used in conjunction with argument
cmplxform, to print elements of the matrix
$A$.
In addition,
x04ddc chooses its own format code when
form is
NULL or
${\mathbf{form}}=\text{'}*\text{'}$.
If ${\mathbf{form}}=\mathbf{NULL}$, x04ddc will choose a format code such that numbers will be printed with either a %8.4f, a %11.4f or a %13.4e format. The %8.4f code is chosen if the sizes of all the matrix elements to be printed lie between $0.001$ and $1.0$. The %11.4f code is chosen if the sizes of all the matrix elements to be printed lie between $0.001$ and $9999.9999$. Otherwise the %13.4e code is chosen.
If ${\mathbf{form}}=\text{'}*\text{'}$, x04ddc will choose a format code such that numbers will be printed to as many significant digits as are necessary to distinguish between neighbouring machine numbers. Thus any two numbers that are stored with different internal representations should look different on output.
More complicated values of
form, to print a Complex number in a desired form, may be used. See the description of argument
cmplxform above for more details.