Cards in the forest

Field widths almost demand intimacy with the input data – across all possible ranges, even. It was probably easier to punch them from cards or prepared, with all significant digits accounted for, from another trusted program. The stored and subsequent printing of inputs can vary greatly, mostly from these elements:

  • user-punched decimal or not ?
  • read() field width for FORMAT is Fx.0 or Fx.y ?

Here is sample output from reading in two numbers with different field widths:

field-width - Copy

And a summary of observations:

  • blanks do not become zero
  • gaps are collapsed
  • arguments are “numbers on a card” and nothing more

The slow down and pacing of yourself

Fortran 77 is pretty specific about its output. I draw a line and split it into boxes, each holding a letter, number or decimal point. That helps me with the FORMAT() calls. Here is what it looks like diagrammed in Excel (but I use paper):

graph-paper - Copy

It takes four notebook-paper lines to sketch out. Between that and flow-chart diagrams, I feel like I am planning programs, designing them, instead of diving straight into coding.