Adding ->V2, RECT and CYLIN to soft menu

• We often need to convert between rectangular and polar form. Lets add these commands to the CUSTOM softmenu.
• V2 builds a two-dimensional vector using the first two stack values and builds in polar/rectangular depending on mode.
• RECT and CYLIN don't convert the first stack value as I thought they did, but instead set the coordinate mode. (Thus displaying ALL stack values in that mode.)
• Source from HP Forum
• invoke: [white] [mode=>custom] # to open custom softmenu
• invoke: {->V2 RECT CYLIN} [enter] MENU [enter] # caps values can be fetched from the [CAT]alog
• In words, put the ->V2, RECT and CYLIN commands in curly brackets, then call the MENU command.

Entering complex values, the hard way

• Make sure complex mode is on
• For rectangular values, enter between round parenthesis with a space. ie 5+j3 would be (5 3)
• For polar values, enter between round parenthesis spaced with angle symbol ([alpha][red][6]). ie 5 at 30 degrees would be (5<30)

Entering complex values, better

• Make sure complex mode is on, otherwise ->V2 will just build a regular vector. With complex mode, it still looks just like a regular vector but the j is implied.
• As described above, setup a custom softmenu with the ->V2, RECT and CYLIN/POLAR functions.
• For rectangular values, switch to rectangular coordinate system, put your two components on the stack, and ->V2
• For polar values, switch to polar system, put r and angle on the stack, then ->V2
• To switch your answer between the two, you can just switch coordinate systems. All complex values are stored in rectangular form and displayed according to the chosen system.