Q66560: "Illegal Function Call" Using Coprocessor in BASIC 7.10

Article: Q66560
Product(s): See article
Version(s): 7.00 7.10 | 7.00 7.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | SR# S901018-77 buglist7.00 buglist7.10 | mspl13_basic
Last Modified: 12-NOV-1990

The following program gives an "Illegal Function Call" error when run
as a .EXE program using a math coprocessor; however, it works
correctly in the QBX.EXE environment or with the coprocessor disabled.

Microsoft has confirmed this to be a problem in Microsoft BASIC
Professional Development System (PDS) versions 7.00 and 7.10 for
MS-DOS and MS OS/2. We are researching this problem and will post new
information here as it becomes available.

Workaround
----------

To work around this problem, do one of the following:

1. Break the complex equation into smaller parts that are evaluated
   separately.

-or-

2. Turn off use of the coprocessor with SET NO87="message" at the DOS
   prompt.

-or-

3. Compile using the alternate math (/FPa) option.

Code Example
------------

a = .475
b = 75
c = 62
d = .007
e = 22
f = (b * e ^ 2 / d) * SQR(1 / ((2 * b * c * a) ^ 2 + (b ^ 2 - c ^ 2))

Simplifying the equation eliminates the problem. For example, removing
the (b * e ^ 2 / d) factor eliminates the error.

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