[tv]

Not knowing exactly yet where this will go/end, but having a pretty good idea as to the usefullness, I'm starting a 
page where I look into constructing mathematical formulas from bwise blocks, where the idea is that these blocks 
construct a formula graphically on the [Tk] canvas of [Bwise] (which is a normal, vanilla, even way back compatible canvas, no extensions either), which can also be evaluated, and in this case I want to make the bwise graph (the 
interconnected blocks) render a complete formula, in preferably [Expr] format, or in [Maxima] format.

So that when a formula has been construted, it can be filled in and used both as tcl expression, or as maxima expression, and preferably all automatically.

[Maxima] allows much more complicated formulas and lets say operators, like integration and differentiation and all kinds of algebraic manipulation, which in this way can be given a graphical interface, which can be quite a complicated 
matter because there are many options, but interesting.

The idea to begin with is that a bwise graph will contain blocks which stand for constants, functions and operators, and that these are connected up according to normal [bwise] logic, see for instance [bwise applications and examples].

In its '''simplest form''', making use of the [tcl] [expr] command, this could go as follows, assume we make blocks based on simple basic arithmetic, such as doubling a number, adding two numbers, etc, as example:


[http://82.168.209.239/Wiki/exaformula1.jpg]

The saved canvasfile:
----
 global bcount scopeindex wireindex shellindex drumindex entrycount moncount proccount seqcount stackcount termindex  textcount 
 set bcount 0
 set scopeindex 0
 set wireindex 6
 set shellindex 0
 set drumindex 0
 set moncount 1
 set textcount 2
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 # now the block related variables\n
 set double.bfunc {set double.out [expr 2.0*${double.in}]}
 set double.bfunc_init {}
 set double.in {8}
 set double.out {16.0}
 set add.bfunc {set add.out [expr ${add.i1}+${add.i2}]}
 set add.bfunc_init {}
 set add.i1 {16.0}
 set add.i2 {52}
 set add.in {}
 set add.out {30.0}
 set divide.bfunc {set divide.out [expr ${divide.num}/${divide.den}]}
 set divide.bfunc_init {}
 set divide.den {30.0}
 set divide.in {}
 set divide.num {52}
 set divide.out {1.73333333333}
 set const.bfunc {set const.out 8}
 set const.bfunc_init {}
 set const.out {8}
 set slider.bfunc {set slider.out [.sl.value.s get]}
 set slider.bfunc_init {}
 set slider.out {52}
 set Text1.bfunc {global mc; $mc itemco [tag_and { Text1 textfield }] -text ${Text1.in} }
 set Text1.bfunc_init {}
 set Text1.in {0.466666666667}

#### Some additional functions and scripting to make a slider to drive the 'slider' block automatically:

 proc slidsend { {n} {v} } {
 #  send "$n $v"
  
 }
 proc slidsendupdate { } {
 #   send update
 #net_funprop const
 #net_funprop slider
 foreach i [net_funct Text1] {net_funprop $i}
 }

 sliders {{value}}

----

The example canvas, simply sourcing in the above one top of [bwise] lets you use it, makes some computation, based on 
tcl [expr] and the bwise graph data flow logic, and even lets you automatically recompute when changing one of the inputs to the computation using the slider.

Every block is a simple computation. (On day I'll make a back-extractor for 'new*' commands based on an exisiting canvas to make nicer sharable canvas files... Unless somebody beats me to it!:)) 

Most people in the computer corner will understand we could also make a single [expr] formula to evaluate the above graphs' computation, and we will now look into how we could do that automatically.