Has anyone any idea where I can get a double precision maths library which will work with the Keil C51 compiler.
"I hadn't expected such a big impact..." Maybe the $5000 is sounding a bit less unreasonable...? "I thought C was supposed to be just about as fast as assembler!" That does, of course, depend very largely upon your skill... And there are some tasks for which 'C' is particularly unsuited - I guess this could well be one of them?
"Maybe the $5000 is sounding a bit less unreasonable...?" Have you seen how little of the standard math library you actually get for your $5000?