Edward Sternin

Oh, I see! Vectors get created even without create! This might be good enough. I'm not 100% clear as to why syntactical compatibility between 2.x and 3.x is needed. Nor why the vectors need to created in a single command. Is this because the TCL code making the call can't be changed? The reason for my initiating this compatibility discussion is this: if I want to write a code that I can distribute (to students, for example) I need to anticipate the environment in which they will be using it. The...

Sorry, @ghowlett, I may have been unclear. It's the loss of ability to declare multiple vectors on one line that represents a discontinuity in syntax: $ bltsh30 % blt::vector create x(5) t w unknown switch "t" The following switches are available: -variable varName -command command -watchunset bool -flush bool -length length although I just noticed that there is in v.2.5.3 from blt-dev an option: vector configure -oldcreate bool which may be doing what I had in mind: The configure operation sets...

postscript BB is off

Very simple but useful things that are missing in v.2.x : [x min] and [x max]. This is difficult to overcome (my shortest version is x dup xx; xx sort; puts "$xx(0)" for min), and the best workaround I found is to use critcl: package require BLT namespace import ::blt::* package require critcl critcl::clibraries -lBLT critcl::ccode { #include <tcl.h> #include <blt.h> } critcl::cproc minValue { Tcl_Interp* ip Tcl_Obj* v } double { Blt_Vector *vp; Blt_GetVector(ip, Tcl_GetString(v), &vp); return vp->min;...

BLT v.3 significantly changed the syntax of the vector command. Since a lot of places are still running v.2.47z, trying to write universal code requires accommodations like these: proc newVector { name len } { # BLT 2.x allowed to re-create existing vectors, # this is necessary in BLT 3 but will also work in BLT 2.x global BLT3 $name if { [info exists ${name}] } { vector destroy ${name} } if {$len != "" && $len > 0} { if {$BLT3} { vector create ${name} -length $len # BLT 3 initializes to NaN, restore...

Just updated the code from this site, compiled and verified that the same behaviour is seen in the current version (3.0? 4.0?) of BLT: $ blt-src/src/bltsh30 fpbug.tcl tclsh underflow with y = exp(-x**2) 25.00 --> 3.681e-272 26.00 --> 2.612e-294 27.00 --> 2.508e-317 28.00 --> 0.000e+00 29.00 --> 0.000e+00 30.00 --> 0.000e+00 blt underflow with y = exp(-x^2) 25.0 26.0 27.0 --> 3.6808558548018004e-272 2.6117417612840555e-294 2.507972e-317 25.0 26.0 27.0 28.0 --> floating-point value too small to represent...

unnecessary and harmful underflow error in vector

By the way, the plotting symbol and other decorations on the plot must also be scaled by the [tk scaling] factor when generating PostScript. Some of it could be done in tcl, so the truly critical part about PostScript is the fonts because one cannot correct it within tcl. Perhaps the best way to specify sizes of things on the graph could be not in absolute terms (pixels or points) but, say, % of the graph width. This approach would scale predictably across modes of viewing the same graph (low-res...